I just did this on my last tank and added about 12 or more extra miles (city). Thats about one days commute. This was for fun and not a precise test.
I believe a lot of gas savings can be found this way by simply maintaining your vehicle.
I’ve been observing drivers as well and everyone is solo and most dont seem to care driving with a heavy foot and still slinging in and out of traffic only to cathc the next light.
John Neff, from AutoBlog, suggested an experiment: Drive normally for a tank of gas, and record the number of miles you get on the tank. Then follow standard gas-mileage reducing tips from places like the US Government and Edmunds.com, and see if you’re able to do any better. I volunteered.