I have a 2015 Chevy spark 5spd. I get an average of 35mpg. The best I've ever got was 56mpg. I was cruising at 45mph-70mph through a mountain pass where I live around. I found out that if I fill up with 92 octane rather than 87 I don't have to shift from 5th to 4th as much as I would if I filled up with 87. Also I get about an average of 8 more mile a gallon if I use 92 than 87. Top tier gas is better mpg as well. I prefer chevron or Texaco. They are expensive but I have done a lot of driving around I found out which one gives me the best. Also I can get like 70 mpg if I fill up on 92 octane n
