Short Version of this post: I bought this bike rack:
Free2Go - The Bike Rack For The Smart (Video:
https://www.youtube.com/watch?v=fyms3-sH0dQ) for use with Car2Go, and I really like it.
Long Version: Six weeks ago I sold my truck and became a full time bike commuter. I had been commuting to work and getting around the city almost exclusively by bike for several months since moving to our new city. As a bit of insurance, I became a car2go member. I'm blessed with both my home and my work place being in the Car2Go home area, and my workplace is a terminus of sorts, so there is always a large number of cars available.
My commute is 19km (12 miles) each way, and about 90% highway. I'm happy to bike through the rainy season, but there are instances when I'd rather not be on the highway on my bicycle. When I work a night shift I finish at 11:45, and one some nights training keeps me late until close to 1 AM. From the time I leave for work until I get home those days are 13 hours. It's nice to skip the bike ride and be home quicker, especially on Friday and Saturday nights (when there are more crazies on the road).
The bike rack itself is super light. It takes up about 1/3 of an Ortelieb Bike Packer Pannier. I envision carrying it with me most of the time, but I could also leave it at work, since I will likely be using it to get home more than getting to work.
Installation is relatively quick; last night was the first time I used the bike rack, and it took me 8 minutes to install. I'm sure once I've done it a couple times I could get it down to 1/2 that time.
One of the attractive features of this bike rack for me was that you could get your bike 80% secured, then unlock the car2go and start your car2go trip . This will reduce the cost of the trip, since you pay for parked time as well as moving time. No sense in paying the $0.41 per minute to install the bike rack if you can do it before beginning your trip. You can also do the same thing at your trip end, undo the strap going under the cars back window, then lock the car and end your trip. Then you can take your time removing your bike.
With the bike on the stirrups and the straps done up the bike was very secure, it had virtually no movement when I tried to push the bike around to check it was tied down.
It's a pretty elegant solution to carrying a bike on a smart car, and it's going to make my car-lite life a lot easier.
I'm not affiliated with the product at all, I just found it while searching for a solution to carrying a bike on car2go. If you've look at this rack and wondered, I can confirm: it works great!