Originally Posted by Joey D
My tires were also right and the recommended psi, which makes a huge difference in mileage.
Totally agreed. I run mine at 40/38 (F/R). As I said ... I calculated 40.41 MPG at 65 for a 220 mile trip with my 5 speed. 70 would yield about 38. 75 would yield about 35 and 80 is low 30's. I'm basing the other numbers on relative MPG changes in the on board display ... not calculations.
I KNOW my car gets right at 40 mpg at 65 (calculated) on the highway. Above 65 MPH ... the drop is significant.
I would suggest that the OP simply try a tankful at 65 with cruise and see what the result is.