save gas, drive 55mph?

[Domromer]

I heard that in the last big oil crisis the speed limit was lowered to 55mph. Why haven't we done that yet? Wouldn't it save lots of gas? Or maybe just truckers would be forced to go 55mph. I imagine that would save many gallons.

What do you think?

[Robert C]

In many states, like California, trucks are limited to 55mph. One problem has always been making it clear just what is a truck. As I understand, vehicles are calssified by the manufacturer. What I am not clear on is why light and passenger trucks are allowed to skirt the laws by meeting federal regulations as trucks; then apply for treatment as autos under state laws.
A huge change would come about of the rule was, simply, once a truck, always a truck.

[lyeinyoureye]

By trucks they generally mean tractor trailers, not light duty passenger stuff. Even then, they'll still go 75mph if given the chance. If enforced, it would create a lot of revenue, save a decent amount of gas, and most importantly imo, drop gas down to ~$1.50/gallon because gas is incredibly inelastic. A one-two percent drop in consumption would send the number of forward days of supply back to ~2000 levels and do the same thing to price. Otoh, by not enforcing it, we end up bumping up against gasoline's inelasticity, meaning it may take going from $2-4 just to drop demand by 1%. Because of this increase in price, government also makes way more from gasoline taxes, so I don't see why they would want to piss off the public/generate revenue by enforcing speed limits when they can have what's likely a greater increase in gasoline taxes thanks to the elasticity of gas.

[maddyfish]

Some cars don't even get best mileage at 55. According to my wifes' cars gas mileage display it gets best mileage at about 64mph on flat ground.

[lyeinyoureye]

Some cars don't even get best mileage at 55. According to my wifes' cars gas mileage display it gets best mileage at about 64mph on flat ground.

Eh... Could be, but usually cars aren't geared that badly. Did you do several alternating bi-directional runs over the same loop within a short amount of time (weather) and CC set at those respective speeds? Make sure the torque converter was locked up in both cases? Etc... For the vast majority of cars, as long as conditions are the same, slower in top gear is better. (http://www.greencarcongress.com/2006/05/fuel_consumptio.html)

[dynodonn]

55 mph speed limit would just slow most motorists down by 10 mph, so that means that the two mini vans with families, loaded with luggage, that split us on I-15 going into Vegas (one fast lane, one truck only lane) at 120 mph would now keep it down to a respectable 110 mph.

[Gus Riley]

We get better than 40 mph at an avg speed of 80 mph with our Jetta. Once we left Illinois on our way to Camarillo, Calf. last summer, we spent most of our trip at around 80, sometimes faster. Round trip we avg 43 mpg. That's good enough for me. At 55 mph I don't really think it would be much better. We don't spend much time at that slower pace.

[lyeinyoureye]

Gasser or TDI? Btw, average is computed by taking the distance over the time, being around or above 80 most of the time probably won't result in an 80mph average. The only way anyone can consistently figure these things out is to actually measure them, accurately and precisely. ;)

[Gus Riley]

Gasser or TDI? Btw, average is computed by taking the distance over the time, being around or above 80 most of the time probably won't result in an 80mph average. The only way anyone can consistently figure these things out is to actually measure them, accurately and precisely. ;)

Details, details. When I set the cruise for 84 mph (because our Jetta speedometer runs about 3-4 miles fast) and leave it at that speed for hours, I think it's pretty safe to say our avg is close to 80 mph.

TDi.

Now our Grand Caravan is lucky to achieve 24 mph at 70 mph. Even less with the Aegis and Tandem on top of it.

[Domromer]

http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2005/10/19/MNG3NFAOF11.DTL

Here is an article that talks more about slowing down to 55.

I think the main problem is a mental one. I want to get there as fast as I can it's all about me. Maybe people should be a bit less selfish and think about how much less fuel could be used if they were willing to sacrafice a little speed.

[Gus Riley]

Something a bit different and slightly off subject course.

Years ago with the first gas crisis in the early 70s, when I was a young punk and still very gullible, an older friend/workmate convinced me that we could drive further in a day at 55 mph than we could at 70. His position rested on his belief that people are less fatigued at 55 mph over the course of a day, therefore they could drive longer. He said driving at 70 mph plus would wear a person out, and they would have to stop earlier. Of course being 18 at the time I believed him, after all he was a fully grown adult and been around to know, right? Through the years with my own mature experience, I have never been able to prove his point. In fact if anything, I have proved to myself that he was full of it. :)

[lyeinyoureye]

Details, details. When I set the cruise for 84 mph (because our Jetta speedometer runs about 3-4 miles fast) and leave it at that speed for hours, I think it's pretty safe to say our avg is close to 80 mph.

TDi.

Well... if you drive at 80mph with no slowing down at all for 8 hours, and spend 2 hours at a 40mph average speed, or some approximation of that, you'll only be at ~72mph. In any event, from everyone I've read, TDIs follow the 120-speed=~mpg rule. Meaning 120-70=~50mpg, or 120-80=40mpg. I'm guessing your trip average was ~75-77mph. ;) If you can stand to keep the cruise at 55mph, you should get into the high sixities (http://forums.tdiclub.com/showthread.php?t=161076&highlight=55mph). Or at 25mph in top gear, ~100mpg (http://www.gassavers.org/showthread.php?t=2353). So, if by not much better, you mean an extra ~20+mpg, then sure. :p

Wrt to what Gus Riley said, it works for me in semi busy traffic, since having everyone pass me means I can just sit back and only worry about what's in front of me as opposed to having to deal/change my speed because of those around me. Otoh, if I were in an area where I could go 70mph non-stop w/ no hassles, then I could probably go farther. YMMV.

[Ekdog]

I heard that in the last big oil crisis the speed limit was lowered to 55mph. Why haven't we done that yet? Wouldn't it save lots of gas? Or maybe just truckers would be forced to go 55mph. I imagine that would save many gallons.

What do you think?

The 55 mph limit saved a lot of gasoline and a lot of lives. It's a shame it was done away with.

[Gus Riley]

http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2005/10/19/MNG3NFAOF11.DTL

Here is an article that talks more about slowing down to 55.

I think the main problem is a mental one. I want to get there as fast as I can it's all about me. Maybe people should be a bit less selfish and think about how much less fuel could be used if they were willing to sacrafice a little speed.

Something else to think about when we slow down. Over the course of a long distant trip, 55 mph speeds might cost us another motel stay. The difference between 55-65 and 75-85 per hour is substantial. Especially toward the end of a long day behind the wheel.

I agree that local driving attitudes that scream "Must Go Faster" are dumb. We all ride bicycles, we all know we will get there and the extra time spent doing it doesn't hurt us one bit.

[Gus Riley]

... If you can stand to keep the cruise at 55mph, you should get into the high sixities (http://forums.tdiclub.com/showthread.php?t=161076&highlight=55mph). Or at 25mph in top gear, ~100mpg (http://www.gassavers.org/showthread.php?t=2353). So, if by not much better, you mean an extra ~20+mpg, then sure. ...


I'll give it a try and let you know how much better it gets at 55, but I fear an increased risk in being rear ended.

[Gus Riley]

The 55 mph limit saved a lot of gasoline and a lot of lives. It's a shame it was done away with.

Is there a reference for this claim? I have heard arguments that refute your claim.

[lyeinyoureye]

I'll give it a try and let you know how much better it gets at 55, but I fear an increased risk in being rear ended.

Just stay in the right lane at all times, unless you need to follow a freeway split or something. Semi drivers are generally much better/more polite compared to the average driver imo, and having more room to maneuver (emergency lane/off the road, depending) are all advantages. If you don't want to go 55, go 60 or 65. I went to Vegas with an average speed of ~60mph in my V6 Camry and pulled ~30mpg, but if I drive w/ everyone else, it'll drop to nearly 20mpg. In terms of safety, it's just a matter of kinetic energy/braking distance. at 40mph, if it takes you X distance to come to a stop, it'll take you 2X at ~55mph, and 4X at ~80mph. Double your speed, quadruple your braking distances. It's not a huge difference in fatalities, since most deaths are from drunk driving or run off the road incidents, but it's something imo.

[Domromer]

You have a lot more time to react at 55mph vs 85mph. Thats a fact.

[cerewa]

I'll give it a try and let you know how much better it gets at 55, but I fear an increased risk in being rear ended.

You could try comparing fuel economy at 65mph and 80 mph.

[Ekdog]

Is there a reference for this claim? I have heard arguments that refute your claim.

If you are referring to the part about saving lives, it looks like you might be right. I had a look around on the net, and it appears that the death toll did not go up as I had assumed. Thanks for pointing out my error.

There can be no doubt about the lower speed limit saving gasoline, can there?

[wahoonc]

If you are referring to the part about saving lives, it looks like you might be right. I had a look around on the net, and it appears that the death toll did not go up as I had assumed. Thanks for pointing out my error.

There can be no doubt about the lower speed limit saving gasoline, can there?

I know at least in NC there was a reduction in the number of deaths, but it was on the secondary roads where the speed limit was already 55mph. The theory is that the number of miles driven dropped and a by product was the number of accidents. However I think the argument that 55 saves lives is valid. Statistically you have a better chance of surviving an accident at 55-60 mph vs 75-80mph. Basic physics...

Aaron:)

[I-Like-To-Bike]

I heard that in the last big oil crisis the speed limit was lowered to 55mph. Why haven't we done that yet? Wouldn't it save lots of gas? Or maybe just truckers would be forced to go 55mph. I imagine that would save many gallons.

What do you think?
I wonder about the direct relevance to those who are (or would like to be) car free. Or the relevance of their opinions on the subject.

[lyeinyoureye]

It's relevant for those who would like to be car-lite and minimize gasoline consumption, and even car-free'ers from the POV of transporting goods. Unless of course they don't consumer anything except for what they can build themselves. But I think those car-free'ers wouldn't be on the forum in the first place. ;)

[Domromer]

I wonder about the direct relevance to those who are (or would like to be) car free. Or the relevance of their opinions on the subject.



Unless you are producing all your own food and products than you are effected by gas and how much is used. It doesn't matter if you are car free or not.

So it makes all opinions relevant.

[Roody]

I wonder about the direct relevance to those who are (or would like to be) car free. Or the relevance of their opinions on the subject.
It really pains me to agree with you, but I was wondering the same thing. Of course, OTOH, decreasing gas consumption worldwide is (or should be) of relevance to everybody. But the best way to do that, in terms of this forum, is to drive less, not slower.

[pseudobrit]

Well... if you drive at 80mph with no slowing down at all for 8 hours, and spend 2 hours at a 40mph average speed, or some approximation of that, you'll only be at ~72mph. In any event, from everyone I've read, TDIs follow the 120-speed=~mpg rule. Meaning 120-70=~50mpg, or 120-80=40mpg. I'm guessing your trip average was ~75-77mph. ;) If you can stand to keep the cruise at 55mph, you should get into the high sixities (http://forums.tdiclub.com/showthread.php?t=161076&highlight=55mph). Or at 25mph in top gear, ~100mpg (http://www.gassavers.org/showthread.php?t=2353). So, if by not much better, you mean an extra ~20+mpg, then sure. :p

I don't know where you heard the 120-x=mpg formula but it's not accurate.

Real world TDI mileage is somewhere between 38 and 55mpg. I've gone as low as 38 on a tank and as high as 56 (I drove 75mph nonstop for 8 hours; fuel tank wasn't empty but my bladder was on F). Average has been 46.

If you're riding around at 25mph in top gear you're going to ruin the turbo. And you won't get 100mpg unless your trip is downhill the whole way, in which case you just ride your bike. These cars are happiest at highway speeds and loads and will return the best and healthiest mileage when in the lowest part of the torque peak plateau (starts around 2000rpm) in the highest gear possible for the speed of travel.

[lyeinyoureye]

I don't know where you heard the 120-x=mpg formula but it's not accurate...

Why don't you go ask the TDI drivers that posted these notes about it. :p Out of curiosity, how would the turbo be ruined by idling down the road at ~25mph? Anyway, just because your mileage is between ~38-56 per tank doesn't mean every TDI (http://www.gassavers.org/showpost.php?p=50291&postcount=114) gets that mileage. The driver can contribute quite a bit to the car's efficiency.

THIS IS AN UPDATE ON THE BEETLE'S SUMMER MILEAGE

As expected, mileage during this last summer (2005) averaged about 65 miles per gallon, when traveling at a normal highway speed of 65 miles per hour. There is a rule of thumb that a car will get 10% better mileage by slowing down 5 mph on the highway. Or, if you slow down 10 miles per hour, your mileage should improve by a whopping 20%. So, you can calculate how well the car would do at a different driving speed. Remember, when figuring speed, you should include any headwind.

In early September, I traveled from Utah to Wisconsin to attend the annual meeting of the TDI Club, an on-line group of VW diesel car owners. I wanted to see just how good my mileage could be-- I drove all the way to the meeting at 55 miles per hour. Early on Wednesday morning, I topped off my tank (filled with 5% biodiesel blend) at Park City, Utah, waved goodby to the attendants, and headed out determined to see just how far I could get. I was blessed by perfect weather, almost no wind, all the way.

I finally stopped for fuel about noon the next day at Davenport, Iowa, a one-tank trip of 1,209 miles. (All at 55 mph, remember. I was honked at four times.) I filled the tank, taking 15.5 gallons. I had obtained a record --for me-- 78 miles per gallon.

[Ekdog]

It really pains me to agree with you, but I was wondering the same thing. Of course, OTOH, decreasing gas consumption worldwide is (or should be) of relevance to everybody. But the best way to do that, in terms of this forum, is to drive less, not slower.
This question is relevant to me because, even though I don't drive and I rely on my bike and public transport most of the time, I do ride along with my wife once a month or so when we drive the 100 kilometers to her beach house. I've persuaded her to reduce the speed from the legal maximum of 120 kph to 100.

Very few of us, I suspect, are 100% car free, so how about driving less and more slowly when we do drive?

[Artkansas]

I heard that in the last big oil crisis the speed limit was lowered to 55mph. Why haven't we done that yet? Wouldn't it save lots of gas? Or maybe just truckers would be forced to go 55mph. I imagine that would save many gallons.

What do you think?

Yes, but the costs in lost productivity and time far outweigh the savings.

[Lt.Gustl]

an engine will get best efficiency at wide open throttle (WOT), most cars are very overpowered in the US. cruising at 55 you've barely got the throttle cracked, while there is less wind resistance the engine isn't operating at peak efficiency. I've found my V8 truck gets about the same MPG regardless what speed I go or wether I'm towing 3k lbs on a trailer. my 250cc motorcycle is WOT on the highway at 80-90mph and get 50-60 mpg depending on if it's uphill or a headwind, going slower I get about the same, stop and go traffic however or through town with minimal braking I will get better mileage. there is a technique used by super mileage cars as well as 3rd world taxi drivers called "coast and burn" where the engine runs WOT then coasts in neutral until the speed slows down then driver floors pedal and the cycle begins again. I experimented with this technique on my 1100cc motorcycle on a long trip and it returned nearly 100mpg, when I normaly would get 50mpg. This is why it is much better to accelerate to your speed of travel as fast as you can rather than slowly build up speed which many drivers falsely think will save fuel.

I remember after Katrina when gas prices first went crazy, the next day going to work on 684 in NY where the speed of traffic is usualy 80 or so everyone was going 55, it was crazy. after a week though and they figured out they used just as much gas as they usualy did speeds went back to normal, if driving 55 saved gas more people would drive slower, but it doesn't in the cars 99% of us own. The double nickle speed limit was a purely revenue based decision, with every other reason under the sun being used to justify it.

a solution many people would arrive to in the days of carburetors and mechanical injection was to put smaller ones on which generaly will increase the torque and decrease the HP at a certain RPM which would result in more efficient cruising.

here are a few links that might help,

http://www.gassavers.org/index.php

http://www.crxmpg.com/

http://utterpower.com/10hp_chevy.htm

http://www.canosoarus.com/03CalifCommuter/CalCom01.htm

Also a great way to save gas and enjoy two wheels is to take a MSF course and get a motorcycle license, that is if your commute isn't practical for biking, which is the best!

[Roody]

My experience riding a bike is that slower speeds require less work than faster speeds. The main reason, as I understand it, is that drag from the air increases as the cube of the speed increase. That's a pretty dramatic effect. Why would this effect be any different for cars?

(I usually manage to mangle the facts when it comes to physics, but i think the concept is correct.)

[Domromer]

Yes, but the costs in lost productivity and time far outweigh the savings.

Really? Did the world stop when the speed limit was 55mph. Nope, it seemed to go on just fine.

productivity must be weighed against quality of life. We as Americans seems to be very productive but as a whole are seen to have very low quality of life.

[Roody]

Yes, but the costs in lost productivity and time far outweigh the savings.
Productivity shmoductivity.

Most car trips in the US are a total waste of time, but more to the point, slowing down doesn't make much difference in the time required for a short trip. If you commute 10 miles, how much time will you save if you slow down from 70 mph to 55 mph. Anybody? Anybody?

[Roody]

Really? Did the world stop when the speed limit was 55mph. Nope, it seemed to go on just fine.

productivity must be weighed against quality of life. We as Americans seems to be very productive but as a whole are seen to have very low quality of life.
Preach it, brother! :)

[lyeinyoureye]

if driving 55 saved gas more people would drive slower, but it doesn't in the cars 99% of us own.

From the first website you linked.
http://www.gassavers.org/showthread.php?t=980
Fuel consumption increase with speed, all things being equal. This means you can't drive at a steady 75mph downhill /w a tailwind and the torque converter locked and compare it to a 55mph run that's bouncing all over the place locking/unlocking the tq, up hill, and into a head wind. The only way for mileage to decrease or stay the same as speed decreases is for BSFC to drop more than, or as much as, the power required to move the vehicle. Generally, this won't happen for high drag vehicles, but it's a possibility for low drag vehicles that have been geared poorly, from the perspective of fuel economy. That being said, there's no way 99% of all cars get the same mileage at 55mph compared to 75mph, all thigns being equal. Just like Roody said...

The main reason, as I understand it, is that drag from the air increases as the cube of the speed increase. That's a pretty dramatic effect. Why would this effect be any different for cars?

[Roody]

From the first website you linked.
http://www.gassavers.org/showthread.php?t=980
Fuel consumption increase with speed, all things being equal. This means you can't drive at a steady 75mph downhill /w a tailwind and the torque converter locked and compare it to a 55mph run that's bouncing all over the place locking/unlocking the tq, up hill, and into a head wind. The only way for mileage to decrease or stay the same as speed decreases is for BSFC to drop more than, or as much as, the power required to move the vehicle. Generally, this won't happen for high drag vehicles, but it's a possibility for low drag vehicles that have been geared poorly, from the perspective of fuel economy. That being said, there's no way 99% of all cars get the same mileage at 55mph compared to 75mph, all thigns being equal.

Whthis tells me is that, in addition to lower speed limits, we also need a law that would require cars to be geared properly for fuel economy.

[lyeinyoureye]

Whthis tells me is that, in addition to lower speed limits, we also need a law that would require cars to be geared properly for fuel economy.

:eek:
:eek: :eek: :eek: :eek: :eek: (I thought everyone had me on ignore!)

Right on! I suppose that law would just be incorporated into CAFE. Imo, fuel efficiency could be increased by ~30% across the board with no change in speed if vehicles were optimized for the speed at which they travel instead of the "top speed" listed in the manufacturer's specs. If you look at the gear ratios available for cars during certain time periods, you can see the change in gear ratios. Most cars built in the 80s actually have transmissions available that allow the cars to run relatively efficiently at ~55-65mph, and most cars in the 90s don't. Recently, with the increase in gas prices, manufacturers such as Toyota have starting offering automatics with taller/more gears, as well as automatically shifted manual transmissions, etc... Anyway, at ~70mph, a fullsize SUV peaks out at ~30mpg, a fuel sized car ~50mpg, and a compact ~80mpg. At 55mph these are different, but I don't think most people would be happy with cars that are drag limited to ~65-75mph.

[I-Like-To-Bike]

Whthis tells me is that, in addition to lower speed limits, we also need a law that would require cars to be geared properly for fuel economy.
For a car free person, you sure are interested in wanting to place a lot of restrictions on those who do drive automobiles and on what they can own and what they can do with it.

Any reason to think it is not just mean spirited sticking it to the man, i.e. those stupid/lazy people who don't share your opinion and political/social outlook?

[Domromer]

Those automobiles effect all of us. GM is not just going to start making cars more fuel efficient, they are going to hang on until they are forced to make changes by the goverment. It's the same with speed limits.

Maybe people shouldn't be allowed to drive huge gas guzzling polluters.

We are now living in the fall out of the Regan/bush me generation. it's time to start thinking about what sense for socitiey as a whole, not just my right to drive an f-350 everyday.

[bhtooefr]

FWIW, Ernie Rogers is a BIT of a nutcase, in case you couldn't tell.

Idling excessively causes the turbo seals, which are held sealed by high boost, to leak oil. And, the VNT vanes aren't exercised when driving like this (idling in 5th at 25 MPH... which isn't even possible on a TDI, the 5th gear is too tall,) and soot up and start to stick, which causes some major issues.

You could get 50-60 MPG realistically, depending on state of tune, which engine you have (ALH (99.5-03) or BEW (04-05,)) transmission (manual, 4-spd auto, 5-spd auto,) in a TDI going 55 MPH. And, if you just stay right, you'll be fine - after all, do you get rear-ended on a bicycle all the time?

If you have a manual ALH, get yourself a .681 5th gear, it's not hard to swap. Search on TDIClub.

And, not everyone gets 60 MPG. My best tank (in an old 86 Golf, so a LITTLE (or a lot) different, but mileage ratings are the same as a 04 Golf, IIRC) is 43.5.

[lyeinyoureye]

FWIW, Ernie Rogers is a BIT of a nutcase, in case you couldn't tell.
Personal opinions aside, it doesn't take a genius to realize that stock tires w/ high Crr and poor aerodynamics can both be addressed with great results thanks to the TDI's lovely BSFC map.

Idling excessively causes the turbo seals, which are held sealed by high boost, to leak oil.Idling the engine excessively w/o load can cause the turbo seals to weep. However, idling down the road really isn't idling per say, since the car still needs, shoot... ~6hp, and the bmep is ~3 bar with BSFC at ~300g/kwh. But, like I said before, why don't you ask the OP?

(idling in 5th at 25 MPH... which isn't even possible on a TDI, the 5th gear is too tall,)Well, according to this (http://forums.tdiclub.com/showpost.php?p=1119636&postcount=12) post and this (http://forums.tdiclub.com/showthread.php?t=166668&highlight=idle+speed) post, warm idle is ~900rpm and engine speed at 2k rpm is ~56mph w/o the taller OD. So, it would seem that 900/2000(56mph)=~25mph is right on, and definitely possible. Again, maybe it's not possible in your TDI, why don't you ask the OG posters about it? :p

Hell, coking up the vanes can be a problem, if nothing but rolling down the road at 25mph in fifth is the case. But a good run through the gears every now and then should clear 'em out. F'n newbs. ;)

[bhtooefr]

According to my numbers, 28 MPH is the idle speed in 5th with a stock 5th gear. ;) I will admit, though, I was thinking of the 1100 RPM throttle sensor value implausible mode, not the 903 RPM idle.

And, you're right about that, on reducing rolling resistance and improving aerodynamics, but I think that the effort is better spent reducing weight and such. (Besides, Ernie could have just started with a Jetta or Jetta Wagon, and been at the same place. No wing needed.) (FWIW, the driving style of the hypermilers (such as Ernie Rogers and Lug_Nut...) is a bit crazy. I hear that Lug_Nut's first Passat was totalled because of his... uh... driving. ;))

[lyeinyoureye]

Weight is one of the last things I'd bother with in a car. With 14" tires, Crr varies from ~.006-.014 iirc, and ~.010-.012 seems to be the norm, so the right tire can cut rolling resistance in half. I'd hate to see any car that's been stripped enough to drop the rolling resistance in half based on weight reduction. ;) I suppose you're not alone in considering us slow-pokes crazy, but if I can increase my mileage by 50% with only a ~10-20% increase in time, I'm there. Of course, once you get into the 50mpg range, for most people the financial incentive isn't there. Back when I had my V6 Camry, 2 hours versus 2 hours 20 minutes cost me ~$15 compared to ~$10. That's like paying an extra $15 an hour to drive faster, too rich for my blood! :D Otoh, my little IDI diesel seems to get 45mpg no matter what, so, eh, YMMV. It's really a shame when I think about... Even something as small as a 10% increase in total efficiency would probably send prices through the floor. :beer:

[wethepeople]

I cant drive, FIFTY FIVE!

Also, people who purposely drive under the limit without reason find me right up on their bumper.

[Domromer]

I cant drive, FIFTY FIVE!

Also, people who purposely drive under the limit without reason find me right up on their bumper.

thats real smart.

[Gus Riley]

Just stay in the right lane at all times, unless you need to follow a freeway split or something. Semi drivers are generally much better/more polite compared to the average driver imo, and having more room to maneuver (emergency lane/off the road, depending) are all advantages. If you don't want to go 55, go 60 or 65. I went to Vegas with an average speed of ~60mph in my V6 Camry and pulled ~30mpg, but if I drive w/ everyone else, it'll drop to nearly 20mpg. In terms of safety, it's just a matter of kinetic energy/braking distance. at 40mph, if it takes you X distance to come to a stop, it'll take you 2X at ~55mph, and 4X at ~80mph. Double your speed, quadruple your braking distances. It's not a huge difference in fatalities, since most deaths are from drunk driving or run off the road incidents, but it's something imo.

In Illinois drivers must stay in the right lane unless to pass. It's the law. Of course very few adhere to it. Semi drivers are less and less professional and courteous as time goes on imo.

[bhtooefr]

For what it's worth, I do drive the speed limit, and do stick in the right lane except to pass.

It's just... if I'm driving, I want to get to my destination in a reasonable amount of time. I also don't feel like (or sometimes don't have available to me) drafting semis at dangerously close distances (like some TDIClubbers have been known to do.)

And, yes, my Golf 1.6NA diesel, before 5th gear went out (waiting on the junkyard to have trannies on sale, then I'm swapping to a gasser tranny that will give me LOWER RPMs) would get 43.5 MPG tanks driving any speed it seemed. I got 43.5 when I was doing top speed testing (90 indicated and I had more to go, FWIW,) 43.5 when I was on the freeway going 65, 43.5 when I was following semis at a REASONABLE distance going 55, 43.5 going 55 on my own.

[gmule]

Have any of you experimeted with making trips by car on off peak hours. I avoid driving between the hours of 7:30AM-9:30AM and again at 4:00PM-6:00PM. I have timed different trips to same places and the time difference can vary as much a 20-30 minutes per trip depending on where I am going. I am lucky that I have a flexable schedule that allows that.

[Vireo]

I heard that in the last big oil crisis the speed limit was lowered to 55mph. Why haven't we done that yet? Wouldn't it save lots of gas? Or maybe just truckers would be forced to go 55mph. I imagine that would save many gallons.

What do you think?

I live in Southern California (and post mainly there). I drive a Ford Fusion 2006. I have FORCED myself to use my cruise control at 65mph and I ma getting 29-31 mpg. I used to have a leadfoot and I can see avg mpg drop below 24 mpg.

Just try slowing down for shorter trips you won't get there much faster driving 75 mph plus you prolly won't have a free lane to maintain that speed. so every time you slow down you have to reaccelerate back to 75 mph and that waste even more gas than staying constant at 75 mph

[gwd]

Productivity shmoductivity.

Most car trips in the US are a total waste of time, but more to the point, slowing down doesn't make much difference in the time required for a short trip. If you commute 10 miles, how much time will you save if you slow down from 70 mph to 55 mph. Anybody? Anybody?
You won't save any time Roody, you'll lose time if you slow down:
10 miles/70 miles/hour = 8.57 minutes.
10 miles/55 miles/hour = 10.91 minutes.
10.91 - 8.57 = 2.34 minutes or 2 minutes 20 seconds.
As part of a daily commute to a job 4.68 minutes/day.
Working 5 days per week gives 23.4 minutes per week.
Working 50 weeks per year gives 19 1/2 hours per year.

Since I don't have a car the more important thing is that slower car traffic means the drivers have more time to avoid striking pedestrians and bicyclists. One of the great things about going car free is you free yourself from worrying about speed limits.