Drove a 5.8 2WD with 285 tires, 3.73 posi for 120k+ miles loaded to >8000# carefully maintained. The speedo/odo was off by about 5% (low), and the road mileage readings averaged ~14.7mpg....In higher elevations it would average in the 16s, mountains 14.5. Best mileage 18, worst, 12.5. These numbers can be bumped by the true adjusted mileage, so true mileages are about +0.7mpg.....But this is driving at 63-64 (except worst mileage quote). As soon as you go over 65 the mileage drops dramatically....At 70 that 14.5 drops about 2mpg....
Since this is about mileage, slowing down below 70 really makes a difference with a V8. Maybe a little less with a V10, but my V10 experience (highway light trailer 70mpg 4000miles) was in the 8-9mpg region....
So if you are worried about mileage go slowly, if not, put your foot in, get there fast and don't complain about the bills!.....
PS The 5.8 gets about the same mileage as my 5.4 3.73......
__________________
Pac NW and warmer places
1995 E250 EB 5.8 2WD on to a new owner
2006 E350 EB Elect Top 2WD
|