Why such dismal fuel mileage??

[Scorpion 210 LTD]

Re: Why such dismal fuel mileage??

What temps do you consider extreme heat?
It's been my experience here that cold temps, below freezing, use more fuel, on both diesel and gas. It takes longer for the motor to come up to efficient temps when its cold and a gas motor will run richer when cold due to harder start up conditions. Wheel spin, tire slip and slower driving along frozen road no able to get into your upper or overdrive gears, all while running the defrost and wipers full bore to keep the glass clear usually makes for lower mileage. Not to mention the amount of time the truck is often let run just to warm up the cab to make it fit to drive. You get no mileage sitting still at idle.
The only mileage loss I see during hot weather here might be the added fuel used to run the AC or time not wanting to get out of the air conditioned cab on a hot day.

True and also note that in cold areas we are now burning winter blended diesel. It has a lower cetane rating making it less "hot" requiring you to get into a bit more to keep speed, etc.

 

[mikesjet]

Re: Why such dismal fuel mileage??

I know for a fact that my sport trac is much better off unladen. Without boat which is a aluminum 16 foot that with trailer weighs around 2000lbs. max. and I get 15 mpg round trip which is 170 approximate with three 10% grade hills in the way. Now I do only get 20 at best on the highway as above unladen. Now I only do what the truck seems capable of, meaning I don't really lay into it and make it do something that really taxes it. When I hit those hills I really wish for a diesel, but with the price of fuel and the difference to gasoline I will take the benzne burner. I know I don't have a very heavy load to tow and I like it.

 

[BillP]

Re: Why such dismal fuel mileage??

I don't have a rig like yours but here's a couple of thoughts.

Starting at approx 60mph there is a humongous dragwall. Wind flatplate pressures jump big at 60mph and increase tow drag considerably...not a little but a lot.

Weight isn't your problem, it's the boat...it's a very dirty tow. Example...I towed a 20' poontoon boat (3000lbs) and then a 20 outboard (5000lbs) with a high milage older V8 Towncar. The pontoon was so draggy the tcar would barely do 75mph with the pedal to the floor out of OD and really stressed the engine if I kept it at 70mph. The 20'r towed at 70mph and the tcar didn't breath hard at all in OD. The 20'r was a aerodymically clean and really showed it when towing. When going on trips I towed the toon at 50 and the other at 70. If I remember correctly, mileage was 10 and 15 as taken from the car's mileage computer.

I think calculating accuracy was already mentioned. If you changed tire sizes from original it can make your number off. Check what's on the door jamb against what is on the truck. If different plug it into this link to see if mph has changed...or check with gps...

http://www.discounttire.com/dtcs/infoTireMath.dos