Gas Mileage

Originally Posted by Bruce

The Car Guys on NPR have said that the best gas mileage is achieved if you keep your vehicle just at the speed where your transmission has shifted into it's highest gear.

25 years ago I sent snail mail to Dick Cepek (of Dick Cepek fame, obviously) inquiring about how to estimate the speed that will deliver optimum fuel economy. I had a new 1981 Datsun (they weren't Nissans yet) 4x4 small truck and the gas was getting expensive.

Dick's answer was to look in your owner's manual for the vehicle and read the section about horsepower. They always publish the maximum horesepower at a particular rpm. The curve is very flat at that rpm, so calculate the rpm that is 20 percent less than the rpm for peak horsepower. Choose which ever gear is appropriate for the situation, and drive by keeping the rpm at that calculated number. This assumes you have a tachometer.

A side effect of this is that if you find a need to accellerate quickly you are already at the speed where the ability to accelerate within the chosen gear is maximized.

So said Dick Cepek.

Having studied engineering once upon a time, it seems to make a reasonable amount of sense to me.

[Bill]

Originally Posted by Jim-NY

I traveled at the same speed as the majority of cars on I 95 which was 75- 80 mph in most areas.
Jim

Jim -

Just bear in mind that the tires on the trailer are rated at 65 mph max. You're courting a high-speed blowout.
Check the Goodyear site at http://www.goodyear.com/rv/pdf/rv_inflation.pdf

Bill

Originally Posted by RockyMtnRay

Depending on you define "windy conditions", I believe I qualify as one who has towed under those circumstances. In May of '04 I had to tow for about 30 miles with crosswinds of 50 gusting to roughly 65 mph as I traveled north on I25 through the outflow below LaVeta pass in southern Colorado. This pass...like most on the Front Range of Colorado and Wyoming...acts like a huge wind tunnel when high pressure is to the West and low pressure is to the East. With a properly adjusted WDH to keep full weight on my truck's front wheels, I had zero problems with directional control and experienced no sway whatsoever. Just to be prudent I was traveling at about 55 to 60 mph (speed limit is 75 in that stretch) and probably could have gone faster but saw no reason to really push my luck. Nonetheless, I was quite glad I was towing with a 1/2 ton truck.

rockymntnray,
Curious as to whether you experienced this wind with your old TV also? If with new, did you ever run into any strong crosswinds with your Cherokee with no sway bars? If so, how did your rig handle?
thanks,
Clarke

[RockyMtnRay]

Originally Posted by angler_2

rockymntnray,
Curious as to whether you experienced this wind with your old TV also? If with new, did you ever run into any strong crosswinds with your Cherokee with no sway bars? If so, how did your rig handle?
thanks,
Clarke

Nope and Nope. Worst situation when towing with the Cherokee was meeting a couple of semis with 25 to 30 mph crosswinds on a 2 lane highway out in wind swept South Park. The Cherokee/trailer didn't even wiggle (though I was expecting it). Sorry but can't offer more.

And yes there really is a South Park Colorado...but it isn't a town; just a really, really huge high altitude, mostly treeless, windy bowl shaped valley. At roughly 30X50 miles in size and an average elevation over 9000 feet, it can hold all of Rhode Island but has a population of only about 700 and only 2 highways cross it.

TRockymntn ray, thanks for the info. Southpark brings back some fond memories. I went to college in colorado with many trips into this area. Don't travel down to colorado much now except to fish a few rivers with some friends from Boulder once in a while.

Just made a trip to pick up our 2720 sl. Went from Casper, WY to Missoula, MT. 600 miles each way with many steep inclines and two mountain passes. Averaged 25.5 MPG at 80 mph going. Got 20 MPG traveling 65-75 MPH on the way back. When slowed to 25-35 MPH in a snow storm for an hour, got only 18.5 MPG.

Without towing and around town: 16-17 mpg
Without towing @ 65-70 mph: 17-18 mpg
With towing @ 55-60 mph: 15-16 mpg TrailManor and truck loaded

[fcatwo]

Tuscany Bandit

You must tow in overdrive. We equal your mileage running solo but are 12-14 towing with OD locked out. We have towed a little faster than you in the past but these days we hold it to 62-65 or so.

Originally Posted by fcatwo

Tuscany Bandit

You must tow in overdrive. We equal your mileage running solo but are 12-14 towing with OD locked out. We have towed a little faster than you in the past but these days we hold it to 62-65 or so.

Yes, you are correct...I do drive with overdrive on except when driving up or down hills. That seems to help using less brakes going down hill and keeps the transmission from searching for a lower gear when going uphill, but on flat land I allways use overdrive.

[fcatwo]

TB

Thanks for the info. That 3mpg difference is an eye opener. As I recall, I'm turning about 600rpm (2200 vs 2800) faster in 4th than 5th so that would account for the difference. I suspect I'm addicted to the pedal response I get in 4th however so it may be difficult for me to make the change.