Mythbusters Tailgate Up/Down
Senior User
Joined: Feb 2007
Posts: 239
Likes: 0
From: sticksville (Walsh AB. CA
Believe it or not. I've read in more than 1 place that the resistance under the vehicle affects milage by approx.3to1 more than above. this is fairly obvious when you stop and notice that the racers spend so much time and money getting their cars low to the ground with as flat of a surface as they can. The rockets they call cars that tend to do the best are almost completely flat to reduce turbulance beneath them.In general,the higher you kift your car or truck,the crappier your milage will be.(if rear ends ect. are equal)
Post Fiend
Joined: Jul 2005
Posts: 8,462
Likes: 4
From: Durant, OK (SOSU)
Yep. Randy has an excellent point. That's why NASCAR cars run so low to the ground as well. You want the air to go around the car, not under the car.
If there was a practical way to seal the bottom of trucks from side to side, it would be done already, no doubts. Ever watch wind tunnel tests on new vehicles? The air coming out from underneath at the rear is an absolute mess compared to the smooth flow over the top.
If there was a practical way to seal the bottom of trucks from side to side, it would be done already, no doubts. Ever watch wind tunnel tests on new vehicles? The air coming out from underneath at the rear is an absolute mess compared to the smooth flow over the top.
Senior User
Joined: Apr 2005
Posts: 115
Likes: 0
I don't want to sound like the A$$ of this forum. But c'mon I drive my truck like I stole it. I love to floor it at the rice burners at the red lights, I love the magnaflow exhaust sound and no matter if gas goes to $5 a gallon, I DON'T CARE!!! If I worried about gas mileage and gas prices I would have spent all my money on an over priced japanese HYBRID, not a gas guzzling 5.4 I'm sorry everyone in this forum, please stop talking about MPG on a big truck forum.
Senior User
Joined: Feb 2007
Posts: 239
Likes: 0
From: sticksville (Walsh AB. CA
Originally Posted by Fxxer
I don't want to sound like the A$$ of this forum. But c'mon I drive my truck like I stole it. I love to floor it at the rice burners at the red lights, I love the magnaflow exhaust sound and no matter if gas goes to $5 a gallon, I DON'T CARE!!! If I worried about gas mileage and gas prices I would have spent all my money on an over priced japanese HYBRID, not a gas guzzling 5.4 I'm sorry everyone in this forum, please stop talking about MPG on a big truck forum.
Personally,I don't think of a pickup as a large truck but that depends on perspective.
Moderator
Joined: Dec 2001
Posts: 22,436
Likes: 17
From: Louisville,Ky.
My front skid plate acts like an air dam under the truck 
I also installed a really nice TruXedo bed cover so I'll see how the gas mileage thing checks out after I can go thru a tank of gas without towing something. I did drive a couple hundred miles the last couple of days. Mostlry interstat @ 80 to 85pmh towing about 3000# and got 12.1mpg. Not too shabby concidering there where some long grades that sucked some fuel.
I also installed a really nice TruXedo bed cover so I'll see how the gas mileage thing checks out after I can go thru a tank of gas without towing something. I did drive a couple hundred miles the last couple of days. Mostlry interstat @ 80 to 85pmh towing about 3000# and got 12.1mpg. Not too shabby concidering there where some long grades that sucked some fuel.
Fleet Mechanic
Joined: Mar 2007
Posts: 1,398
Likes: 1
From: Simi Valley, CA
actually some cars do have the bottom paneled, the old DeLoreans have the bottom completly covered with metal paneling with a surface like that of a golf ball, and i know that some volvos and mercedes have the bottom covered in paneling as well, but i think the gas mileage you lose lifting the truck is hardly from the turbulents below it, cuz if you lift it high enough, the air goes right under with no problem (so do small aniamls, children and ricers)!! i think its more due to the weight increase and mechanical disadvantage included in the lift, not the air flow
FTE Legend
Joined: Aug 2004
Posts: 37,887
Likes: 20
From: North Central Rural Sask.
Originally Posted by Fxxer
I'm sorry everyone in this forum, please stop talking about MPG on a big truck forum.
Fuel mileage is a valid thing to discuss, everyone wants the most bang for their buck, including getting the most performance and economy for the fuel they put in!
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Posting Guru
Joined: Apr 2004
Posts: 1,921
Likes: 0
From: central TX
Lifted trucks will also be exposing more moving air to their axles, suspension and tires. That air dam that was designed to push air under these things is likely now pushing it directly onto them. Wider tires will also catch more air.
Senior User
Joined: Apr 2005
Posts: 115
Likes: 0
Like I said I'm not trying to start fights, but a big truck is anything that is 4x4 and will never see 20 MPG. As you all know with a 5.4 and 4x4 you are lucky to average 12-15 MPG and anybody who is getting more then that is using some sort of top secret electric power!! My biggest point was if you are going to talk about MPG then you should drive a little toyota like my brother who gets 40-45 MPG <- now thats something to talk about.
Oh by the way the new chevy siverado claiming 20 mpg is the 2wd lower to the ground. Everyone is correct about the lifted trucks and the air under the truck.
Oh by the way the new chevy siverado claiming 20 mpg is the 2wd lower to the ground. Everyone is correct about the lifted trucks and the air under the truck.
Postmaster
Joined: Dec 2003
Posts: 2,833
Likes: 0
From: Honkytonkville
I've said it before but, my new truck gets 13 MPGs while towing on local highway(powerstroke)...so if I have a truck on my trailer- that's 2 vehicles on the same 13 mpgs....so.....13x2=26 MPGS!!!! I've got this figured out. Instead of carpooling we just need to tow each other's trucks to work and back. That way we can get good mileage 
and all still have our own vehicles 
and all still have our own vehicles
FTE Legend
Joined: Aug 2004
Posts: 37,887
Likes: 20
From: North Central Rural Sask.
I guess my 97 f150 4x4 with the 4.6 that gets 21 mpg on the highway is a little truck!
I guess my 03 f250 4x4 with the 7.3 that gets 23 mpg on the highway is a little truck also!
Good to know I can park in the compact parking spaces now
I guess my 03 f250 4x4 with the 7.3 that gets 23 mpg on the highway is a little truck also!
Good to know I can park in the compact parking spaces now
