Topper while pulling TT help MPG?

I also carry a canoe, and maybe it helps the mileage by .2MPG or so. But towing speed, and wind speed and direction are bigger factors.

The aerodynamic effects you see on 18-wheeler trailers are trying to get a 2 to 4 % increase in fuel mileage.

If you drive 100,000 miles per year, that can be a substantial savings which might pay off the $5,000 investment in aerodynamics in a couple years.

If you tow 6,000 to 10,000 miles per year like me - it will take close to 20 years to pay off the cost of a topper. I have one - to keep my stuff dry and safe.

Rbertalotto wrote:
Used to carry a small , pointed bow, rowboat on the top of a station wagon towing a TT. Bow forward. Dramatic improvement in MPG.

I often carry a canoe. No change good or bad while on the roof. I have had a "little" increase with the no canoe and the toneau cover on the truck bed, but it does depend.

Slowing down is the only way to improve mileage.

Used to carry a small , pointed bow, rowboat on the top of a station wagon towing a TT. Bow forward. Dramatic improvement in MPG.

midnightsadie wrote:
X2 those crazy two guys on TV, showed it made no difference.best fuel mpg is to slow down stay at 55,to 60 mph.

x3!

Not sure anyone has said exactly this: It would not surprise me if a topper affected MPG a little.

But what most of these posts correctly point out is that most campers are HORRIBLE aerodynamically, so the effect of the topper is going to be very mild (if positive at all).

When you look at all the doo-dads that semi trucks have (air dams on cabs, newer curtain things below trailers and sorta-partial-tail cones, I would not want to totally dismiss the effect of a topper, but you also need to consider that a truck is running "nearly-continuously" so those savings add up a bit quicker.

So yeah, if you want to boost your mileage meaningfully, slow down. Get the topper to provide a good, dry cover.

The words 'towing' and 'MPG' just do not belong in the same sentence. They cancel each other out.

Big fuel costs is just something to budget when planning trips.

camp-n-family wrote:

This was proven to be untrue. Air over the cab would flow into the uncovered bed and cause an eddy effect which would then deflect air over the bed of the truck. It actually reduced drag. This is why it is better to drive with the tailgate up instead of down. A covered bed had minimal to no effect on improving aerodynamics. I believe there was even an episode on myth busters about this.
https://youtu.be/r3aqHbD-O9E

Not just Mythbusters. Both Ford and General Motors did their own wind tunnel testing and found tailgate up gives better mileage. But some old internet myths never die.

downtheroad wrote:
We gave up on "good mileage" when towing...not going to happen.
We have a topper because it protects the stuff in the bed of our truck, like the bikes, etc.

Best answer.

Ron

We gave up on "good mileage" when towing...not going to happen.
We have a topper because it protects the stuff in the bed of our truck, like the bikes, etc.