I did an economy run competition last month and experimented with engine-off coasting. Didn't want to do it in the Yaris because it was too new or the BMW because it was too expensive... didn't want to replace the starter in either of them! But, in the beater Miata, I don't care. I can get a used starter for $20-30.

Anyway, I wired up a "kill switch" and stuck it (literally stuck it... with duct tape) next to the shifter so that I could pop the car into neutral and immediately kill the engine without having to reach for the key. The route was about 200 miles and was time-limited so that we averaged about 40 mph. (that doesn't mean we were able to cruise at 40... that included stops... so we were driving 50-60 where we could to make time) I was mostly pulsing up to anywhere between 50 and 65 and coasting down to 35-40 before restarting and accelerating back up to speed. This netted me about 48 mpg in my 1.6 Miata. I was hoping for 50, but didn't quite get it. (will next time because I've added a hard top and deleted the right side mirror)

Around town, I'm getting 32+ depending on how I drive. I took out my temporary kill switch. When I get around to putting one back in, I'll have the potential to easily get 40 mpg in the city.