I at times have seen the fcd go to 80 mpg while going 65 - 70 miles per hour. That is going on a flat freeway ( not going downhill..lol) It usually doesn't last for too long maybe a 1/2 to a mile at a time. My normal speed is 55 - 60 miles per hour. I think not just temp. but the road surface has alot to do with that. It's mainly on this one section of freeway, but on rainy times I've seen it barely hit 50mpg on the same section. Kevin

2004 silverblue 5 sp.