Will the smart car run on Regular is bad for the car? Thanks for you help!
I did a 2000 mile test on my 2008 Passion Coupe, 4 tanks running 92 octane and 4 tanks running 87 octane. I got significantly better mileage with premium (41.0 mpg) than with regular grade gasoline (36.8 mpg). The mileage was enough better with premium that, even with the higher cost of premium, I got a slightly lower cost per mile with premium ($0.10) than with regular grade gasoline ($0.11).