Interstate vs. secoundary roads?

Thanks for the responses. Flip

rwbradley wrote:
I am curious why I am the odd one out. I am quite certain on my mpg findings, the computer in the car even confirms them. I would say that it is likely that there is no one answer as it probably depends on the TT/TV combo. In my case I have a small TT being towed by a gas SUV and am well under weight, however the TT is not very aerodynamic, and when driving at 60mph I am at about 2200rpm, when I get to 65mph I am at 3000rpm and I lock out overdrive to keep it from constantly hunting. My guess is that the biggest factor is gear ratio/rpm's. Regardless in my case because the sweet spot is 60 and there is a huge hit on mpg when I go up from there, secondary highways, even with occasional stop and go is hands down the winner for mpg.

This could also be due to the nature of the secondary roads. Around here, secondary roads go through lots of small towns, which means lots of stopping/starting. That eats into the gas mileage quickly.

I use as much Interstate as possible to get to my destination. Here in Illinois, we have a lot of small towns where the speed varies up and down and up and down when traveling the backroads....Gets annoying. But to each his own. :)

atreis wrote:

rwbradley wrote:
I am curious why I am the odd one out. I am quite certain on my mpg findings, the computer in the car even confirms them. I would say that it is likely that there is no one answer as it probably depends on the TT/TV combo. In my case I have a small TT being towed by a gas SUV and am well under weight, however the TT is not very aerodynamic, and when driving at 60mph I am at about 2200rpm, when I get to 65mph I am at 3000rpm and I lock out overdrive to keep it from constantly hunting. My guess is that the biggest factor is gear ratio/rpm's. Regardless in my case because the sweet spot is 60 and there is a huge hit on mpg when I go up from there, secondary highways, even with occasional stop and go is hands down the winner for mpg.

This could also be due to the nature of the secondary roads. Around here, secondary roads go through lots of small towns, which means lots of stopping/starting. That eats into the gas mileage quickly.

frictional losses in an engine go up as rpm squared, so going from 2200rpm to 3000 rpm increases frictional losses in the engine considerably. that really affects your mileage as well.

Fliposo wrote:
I was wondering if driving the interstate using cruise countrol would save much gas verses the slow down, speedup of going thru towns? My truck seems to have a sweetspot towing of 63 mph.

For gas savings, I have to go with the highway. I use the highways going north here in Michigan, because the roads, north of Lansing, aren't too bad and I can cruise at 65 mph generally without having to pass anyone. Easy.

I will never take I-80 out west again. Coming back home on US-2 was sooooooo much better. Easy. Comfortable. The highways I took in Indiana and Illinois were an absolute shambles and parts of them in South Dakota were too. Yuck. NEVER AGAIN!! LOL