Interstate vs. secoundary roads?

[Fliposo]

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.

[rhagfo]

Never worked to figure it out. I tow mostly on secondary roads due to my location and preferred destination of the Oregon Coast. We did hit I5 north for a trip to Mt. Rainer this year. I needed to down shift far less often as there is no 45mph, or 35mph curves you need to slow down for.
I have also been caught in traffic backups on 101! Stop and go and lots of hills. That will make for some bad fuel mileage.

[rwbradley]

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.

[Bumpyroad]

Drbolasky wrote:


On edit: Is the scenery on the interstates more boring? Yes, no question. I try to plan trips to be a mix of interstate and secondary roads to keep things interesting.

if a road goes thru a section of real estate, it looks exactly the same regardless of what you are driving on. now if you like creeping thru small towns and speed traps, then the side roads excel.
bumpy

[christopherglen]

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.

[atreis]

I get better mileage on the interstate, and use CC if it's reasonably flat.

[Dick_B]

X2 to Ductape's comments. CC will really dump the fuel to the engine to keep up the selected speed when going up a rise/hill/mountain.

[RCMAN46]

I just finished a 2500 mile trip with a 2012 3.6 R Subaru towing a 2600 lb utility trailer.

Now I know this is not an RV but this somewhat relative.

Most of the miles were in California where the towing speed limit is 55.

On the very rough Interstate highways where I was able to maintain 55 with cruise control I was getting 24 mpg.

But on the very smooth state highways with towns about every 10 miles the mpg dropped to about 18.

Most of the state highways were much less stressful and a much smoother ride.

I drive 55 in California as I have out of state plates and do not want to be a selective enforcement victim.

[Drbolasky]

IMHO the consistent speed of the superslab (interstate) will give you better mpg results every time. Stop & go traffic yields dreadful gas mileage as you have to overcome inertia to get your rig up to speed time & time again.

Years ago we were stuck in I-95 near Fredericksburg, VA and in that mile after mile of stop & go I could just about see the gas gauge going down.

On edit: Is the scenery on the interstates more boring? Yes, no question. I try to plan trips to be a mix of interstate and secondary roads to keep things interesting.

[rwbradley]

I found going out East last summer (over 2000km round trip) that the answer was a big no for me. The sweet spot for my TV/TT combo was abt 95km/h (60mph). Going over that point even a little bit made a huge cost in mpg (just going up to 65mph was enough to make mpg go downhill by 25%. Driving thru Mennonite country between Watertown and Lake Placid and across US2 from Lake Placid to Bangor was great, the mpg was much lower, and yes there were small towns along the way with the occasional stop sign or traffic light, but we found the days went much quicker because the drive was much more interesting than on the freeways. The 401 in Ontario and AUT20 in Quebec were a much more boring (and slower feeling)ride even though they shaved a few hours off the return trip, I wished we had taken secondary highways on the return as well.
I am in the process of planning next summer's big trip down the US East Coast (Ontario to Delaware, down the coast to Myrtle Beach, and back thru the mountains in VA/WV. I have been going out of my way to find scenic secondary routes, with the realization that keeping my speed below 60 will save me more money than the cost of an extra night in a KOA due to the extra time needed.

[Ductape]

I always get better mileage on interstate; for best use your foot not the CC.

[Old-Biscuit]

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