65 in 4th is about 3,500 rpm. AF is high 15s to low 16s on flat ground. Vac is around 7-10 Hg. If I try to stay between 60 and 65 in 4th I get 17 mpg.
75 in 5th is maybe like 3,250. AF is between 13 and 14. Vac is around 1-5 Hg. If I use 5th I can only get 14-15 mpg, even if I go slower.
QUICK MATH..
If you drove 50 miles at 65 MPH @ 17 MPG
Gas is $3.00 per gallon
Your fuel cost is $8.82
You would reach your destination in 46.2 minutes
If you drove 50 miles at 75 MPH @ 14 MPG
Gas is $3.00 per gallon
Your fuel cost is $10.71
You would reach your destination in 40.0 minutes
At 75 MPH you would arrive at your destination 6.2 minutes sooner…. but it would cost you $0.30 per minute.
It would cost you $1.89 more in fuel driving that distance at 75 MPH.
Gnarls.
.... stink & pomp
