On interstate highways we average 60 mph and find it both a comfortable and fuel efficient speed. Since we typically limit a days travel to 350 miles max keeping at 60 MPH has little impact on total travel time. Furthermore, should we spot something interesting, like a Cabelas, Bass Pro, or God forbid an antique shop we have time to stop.
If memory serves I think the optimal highway speed for fuel efficiency is 55 MPH. I believe the following MPG decreases over 55 MPH are close to accurate:
- 60 MPH - 3%
- 65 MPH - 8%
- 70 MPH - 17%
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Jeff & Karen
2013 Ford F250 6.7L CC SB
2014 Cougar 333MKS
Huntley, Illinois
formerly Norton Shores, Michigan
