Cat was rattling and had all stock exhaust on my 93 dakota 2wd ext. cab V8 and was averaging about 10 mpg with not a whole lot of highway driving at all.

Put on a mandrel bent single in dual out flowmaster 44 exhaust system, with no cat.

Wondering how much of a difference in mpgs this will make?

How about a tonneau cover, does that really improve your mpgs as much as they are supposed to?

Will an eletric fan do anything mpg wise, or is that just for performance?

Any other inexpensive thing I could buy or do to improve mpgs besides the gutted interior mod?

 

That is absolutely impossible to say how much that will improve gas milage, but it should help if your cat was messed up.

I don't believe a tonneau cover will make a difference... if you've ever seen a truck in a wind tunnel you'd understand why. The bed does not produce a concernable amount of drag on the truck... what happens is a pocket of air forms in the bed which causes the air flowing across the truck to roll over that pocket. A tonneau cover will just replace that pocket of air with a solid object but the same effect will take place. In fact, thats actually why you will get worse gas milage if you drive with the tailgate down... cause that pocket of air will fail to form and the bed will start causing lots of drag.

But the vast majority of the drag on a truck is caused by the wall of a front end these things have! They were never designed to be aerodynamic!

An electric fan will definately help, but its hard to say by how much. Chances are you won't even see a 1 mpg gain from it.

The biggest thing to save on gas is to keep your foot out of it and drive like you have some sense... in other words, if you see a red light up ahead, get off the gas and coast, and if you are driving where there is bad traffic and/or a lot of traffic lights in a row, keep your foot out of it!