Interstate vs. secoundary roads?

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

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.

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. :)

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.

Thanks for the responses. Flip

You best mileage will be at a constant speed. It takes a LOT of energy to get your rolling house up to speed just to slow down again. If mileage is your goal then the interstate is where it's at.

christopherglenn wrote:
Your best mpg would be constant throttle, bleeding speed on the up hills, recovering it on the down hills. Ok constant throttle everywhere but the down hills, less throttle there to keep from speeding.

X2. Theory and personal experience on better mpg agree for me on this.

Besides mpg, if you want to get somewhere farther and faster and with less fatigue, and a bit better mpg, a freeway/highway is the better option. I only use CC on flattish stretches and if there's no buffeting winds. I keep to max. 65 mph too.

I totally love towing our TT on the secondary roads and have towed in places like through the Redwood forests in Cal., along the Oregon Coast, around the Olympic Peninsula and Hwy 2 from Seattle up Stevens Pass and on to Spokane, all of which have a lot of twists and turns, hills, speed limit changes, stop and go, and can be quite windy in spots. I don't know for sure, but I'd guess we lose up to 2 mpg at the worst. I just let T/H mode do it's thing. For me, I find that secondary roads can be a lot more fatiguing and I can't/don't drive as far and I usually try to make it a more leisurely drive and don't drive with a heavy foot on the throttle.

When I can see ahead that I need to stop or slow down, I try to gradually slow down and then gradually pick up speed again. A bit easier on brakes, drivetrain and mpg.

D'OH, if 60 is the sweet spot for getting good mileage, you can certainly drive that in the right lane of the interstate. I do.
bumpy

4aSong wrote:

Old-Biscuit wrote:
We traveled FT for 7 yrs. and took secondary/back roads as much as possible.

Hate traveling Interstates. Boring, idiots that don't know how to merge, road surface beat up, heavier traffic etc.

MPG difference.....never really noticed any. When pulling a 14K 13'4" wind sail we got 10.5--11.0 mpg regardless

X2 - Agree with Old Biscuit.
Back or secondary country road are our 1st. choice and are more scenic. We never considered the MPG difference as we just enjoy what the secondary (country) roads have to offer over the interstates which are definitely boring.

x3. I'll take secondary roads even if it is longer. more scenic, neat stuff to see in small towns, nice places to stop, found many interesting towns, museums, restaurants, places to stay on backroads.

Travel about the same speeds either way, so doubt the fuel mileage is much different.

If you can drive secondary roads that do not have many speed zones through towns, you will get very good mileage. Otherwise the interstate will yield the best mileage unless you hit congestion.

Although I enjoy driving the secondaries more than freeways, I still work full time and have limited time off to get to desired destinations (typically plan for 500 miles days) that preclude long stretches on slower roads.