Those of you who have had one, did your fuel mileage get affected at all by having a truck bed cap on? What about the caps that the roof steps up on? Thanks.

 

I know I have heard people claim when they put the bed cap on, it actually increased their fuel mileage. I'm sure that is why you are asking. I would think the ones that step up add wind resistance, and reduce fuel mileage. I couls see the ones that are even with the cab streamlining the rig, making it a little more fuel efficient.

 

Here is some stuff for you to read on this and related topics. They covered it all very well, so I am not even gonna rehash it here.

Here, Here, Here and Here.

I have run with my cap on and off. I notice no difference at all. Then again, I don't really pay too much attention unless I am losing mileage something ridiculous. It costs what it costs is the way I look at it.

 

I'm not considering a cap to increase mileage, its to keep stuff out of the weather. I'm getting tired of not being able to do something because its pouring rain or snowing. I was going to buy one for one of my trucks and was just curious about its side effects, especially one that steps up since that would give me the most covered space. Keith1992, thanks for the link showing the test w/ the caps and bed covers. Anyone have any info on how a top w/ a stepped up roof affected their mileage?

 

I have been running various designs of bed caps since the mid 1970's on various brands & bed sizes of pick up trucks. The mileage differences rarely ever exceeded 2 mpg. I contribute that primarily to the difference in weight being added and a very small amount of increased wind drag. I use it for the slight increase in security it provides at places like flea markets or stopping at more than one grocery store while we are out shopping. Keep in mind the lock in the T-handle is generally a low end style and can be easily manipulated. It still keeps an honest person honest and removes the temptation for someone to just reach in and grab something out of your bed & makes it more difficult for them to grab your tailgate and drive off. To me the added security by not having to jam everything into the cab before going to the next store more than justifies making two trips to two stores or having a loss of a mpg in mileage.

 

My over all mileage since I bought my truck is 18.51 with 80 to 85% city driving. Best was 25.16 and worst was 9.55 - in Iowa towing into a 35 mph head wind. I've had a canopy or almost from day one - I bought the truck in new Jan 1993 and have tracked every drop of fuel since new.

Bob

 

I have noticed little mileage gain (1mpg maybe) with a cap on my truck. I think that having an extra 300 pounds is really nice when running empty. It helps keep the rear from bouncing around on bumpy roads.

 

I gotta get off topic and say man it must be awesome to have bought one of these trucks new and still be driving it today. And over the years while you put more miles on it the technology has gotten better but your old 12v is still running strong and making more power with simple tweeks than most new diesels. If I wasnt 12 years old in 93' I would have bought myself a lifelong first gen too. lol

 

I said for years - prior to '93 - if Dodge built a serious Diesel I would buy one. You might say that I am happy with my investment.

Bob

 

Thats is a good point. I had never reallt thought about that. It would be nice to be able to have a little extra weight in the back when it rains, especially with a dually.

 

I have a fiberglass shell that is stepped up and my mileage hasn't changed at all since I put it on. It's still between 19 and 20 mpg.

 

Actually, you likely would NOT have been able to do so. By the time people realize a good model got made, its about the same time they stop making them. The car companies and several aspects of society (smog testing, rules about driving autos with salvage titles, financing, insurance, etc) are built around the idea of throw-away cars and trucks. They do not want you to buy a car and keep it for 20 or 30 years.

I don't give a #$%! what they want, I do it anyway. In the next few years, I'll probably buy a new truck and maybe a new car to go with it. And I probably will be several years into retirement before I do it again.

 

quite a few yrs ago one of the car mags tested camper shells for fuel mileage claims [1. flat top and 2 w upturns on the back aka kamm style]. they put them in a wind tunnel in LA somewhere. no increase in wind slip. they also tried them with the tail gate up and down. again no difference. the mind plays tricks with fuel mileage figures. tc.