Why don't trucks go 55 for fuel efficiency?

When the truck is moving, better mpg equates to a much lower gph. The greater engine hours don't matter.

 

My understanding is run time isn't as accurate of a measurement of engine wear as revolutions is. It will typically save fuel at the lower speed, depending on how it's geared, despite running longer. And it might also spin less times even though it's running longer.

Or look at it this way: a truck engine will spin many more times at 1000rpm than it will at 10000rpm.

 

It’s exactly this. If you want me to drive slow, pay me by the hour. If you want to pay me per hour the truck better pull.

 

It's interesting thread. Last year my fuel cost was $32K and change.

And the haters immediately said that's impossibly low lol.

 

The engineers calculate almost all engine wear & maintenance parameters on fuel burn, and converted to miles/hours for convenience. If you go look at service intervals on any of the new Detroits, they're all based on fuel mileage.

 

Don't get me wrong, I keep an eye on fuel prices and usually fuel at the cheapest options, but I don't care so much about cost or economy rather than the % of revenue.

Year to date I'm @ 18%

 

I can't begin to tell you how many guys pass me, and are the first one's to the construction zone or the back up.

Some do two or three times in my 3 or 4 hour driving period.

 

Dont remember if it's been mentioned, but another detriment to going faster is the faster you're going, the more often you have to slow down and speed back up. People say maintaining a constant speed is essential to good mpg. Slower drivers have an easier time of that simply because they're less likely to run up on someone slower than them.

 

I rarely drive over 70. Even hauling cattle I’d drive 70 all day. And the 80mph guys would pass me multiple times over the next 1500 miles and we’d all be within about an hour of each other when we hit the feedlot.

These days I’ve started slowing down on congested routes. Used to drive me crazy trying to run 70 across Iowa while trying to dodge all the 65 mph trucks. Now a days I’ll run 60 when I have time and let the 65 mph trucks dodge me.

 

This my current trip. 64 mph cruising. Trusty Cascadia with APU. 24 miles bobtail included, no other deadhead.

 

Nice, I'm usually around 7.4 with a 10 speed.