Commuting - Faster in the Morning or the Evening?

I have 40 mile round trip suburban commute, equally hilly in both directions. I originally expected my morning commute time to be faster than my evening commute time, because I would be less tired in the morning than the evening. Also, there's less traffic in the morning than the evening, so the traffic lights tend to be more in my favor in the morning. But my evening commute home is consistently faster. I think that's because the workday is over and I'm pumped to get home. What's your experience?

My morning commute is faster because I do less climbing going in than coming home.

It's almost 50/50 in terms of effort. But since it's more downhill going to work, I'm slightly faster by about 10% going to than from.
Depends on what I plan to do I guess.

If I'm going for a long 40-50 miler after work, I take it easy going in.
If I have nothing to do and it's early in the week, I push hard going to and back.
But if it's a hot day, I'll take it easy going in to avoid the sweat and push hard coming home.

I take it easy going in because I need to get through whatever the work day throws at me, including dealing with disasters that can turn into allnighters. Ofcourse if a fellow commuter throws down the gauntlet for a bit of a race I have been known to oblige. ;)

I take a longer way home and then it's hammer time :D so it takes more time but at a higher average speed.

On most days, my morning commute is much easier, ergo faster. My commute is mostly through Ohio farm country, which is fairly flat for the most part. Consequently, the famous northern westerlies hammer me on my return commute, which is of course a drag.

My leg home (22mi) is faster. Predominately downhill, even though the harder gradients are in this direction. My leg to work (22mi) is one false flat after another. The prevailing westerlys should be kicking in soon and that will make the ride home even faster since i live due east from my office.

My 18 mi round trip goes considerably faster in the morning, due to the fact that I'm running straight thru a city and the traffic is way more swamped during evening hours (both bike lanes and car roads).

the morning 12 miles is faster b/c mostly downhill, in the afternoon mostly uphill and I do a 20 mile bike ride in addition to the commute

My ride home is faster - going in, generally average 26.5Km/h, home 28Km/h.

I am not a morning person and it usually takes me about 20mins into the ride before I can get the rythm going... Going home I am usually pumped and ready to stretch myself!!!

I go up a mountain to the office in the morning. Going home it's downhill. Whee!!! :) But I am not warmed up in the morning when I first get out of bed so it takes me at least 30+ min of cycling to wake up, but by that time I'm already climbing the mountains.

My ride home is a slow rise and takes about 2.5 hrs (32 miles). The ride in is much better, about 2 hrs. I do 1/2 one day and 1/2 the next. The afternoon ride stinks, but the morning ride is wonderful and makes it all worthwhile.

It's downhill all the way to work, and uphill all the way back. Plus the route back is longer because I take a detour to avoid a busy road. No prizes for guessing which one is faster.

My evening commute is usually slightly faster because there is slightly more downhill and less uphill on the way back. Also, being a student, I often ride back at unusual (i.e., not rush hour) times, so the traffic isn't so bad. And, I guess, I also like the idea of returning home. :)

I ride slow in the morning since its so quite at 5:30am why not enjoy it. On the way home at 2:30pm I ride hard.

It's downhill and with the wind on the way to work. But when I had the wind on the way home, my fastest time was only 4 minutes slower than the best time to work. I ride hard both ways.