[doclees]

My 95 Jeep Wrangler 4.0 has been a real lesson in general efficiency. I've found that the largest gains in gas mileage has to do with reducing drag. I reduced tire size and weight with no real difference. Removed the roof cage with a 10% increase. Drive slower with another about 10% gain. Added a stock fit K&N filter with no change. With what seems to be no change but I will report more on this later. Dropped 10% from neglecting to watch tire pressure from 40 to 32 lbs. Added ethanol fix to gas without change. Again this I will hold judgment on because it was the same time I missed the tire pressures. I do these changes not for saving money primarily but need. Needed new tires because they were bad on wet roads. Needed new exhaust from rust and stainless won't. Was going to add a matching set of headers and free flow cat but my exhaust manifold is rust free at this time.
I wasn't going to bother with watching gas mileage because it is a purpose built vehicle. But I have a friend, who tends to be a BS master, said he would average 25mpg and a max of 27mpg. Someone else wrote on his JY that hit the 30 mpg mark on a long trip. So I started to wonder how efficient was the 4.0. Can't find anyone strange enough to put this engine in an aerodynamic body until I see the older AMC Eagle. But I was wrong and the drag coefficient is rated higher at .55.
So I guess I will play with belly pans and dams. If upon keeping tire pressure at 40 psi I gain over 24 mpg I will need to reconsider the cat-back and or the gas treatment.