i know you have prolly heard this question over and over. but seriouslly for a ford f150 4.2l v6. what really helps increase mpg and dont say stay off the gas dont lay into it. i mean parts air filters, fuel filter, oil, programmers, what really is proven to help. (im about to get a replacment air filter k&n filter to increase a little bit of mpg)

 

honestly, you will spend a lot of money on parts to improve mileage with only a marginal gain. keeping your right foot from becoming a lead weight on the pedal is really the best thing. i you are looking to primarily gain performance with the benefit of slightly improved mileage, go for it. the big things off the top of my head would be exhaust, a new cold air intake (get the k and n intake as well as the filter), and a programmer.

 

Back off the throttle is the biggest thing you could ever do! I didn't believe it until my new ScanGauge 2 showed me these numbers:

55 mph- 1,900 rpm - 10% throttle - 22.5 mpg
75 mph- 2,650 rpm - 20% throttle - 16.5 mpg
85 mph - 2,900-3,100 rpm - 30-40% throttle - 9.0-12.0 mpg!!!

4.2L V6 - 3.55 5-speed w/ OD

bu for parts, get a K&N. personally i love my -77 series. looks good and adds noticeable power and fuel mileage gains if you can keep your foot from flooring it just to hear that big air intake suck in gulps of air.

 

all those will help, but if you combined those with some new gears 4.10's you would be happy!

 

Before I was getting the normal 14mpg that many people where complaining about. Now I have under $1000 in parts that have helped to get my average of 19 mpg. (I drive fast) 75- 85 on the Highway.

Xcal2----- $412 shipped-- was set on 91 perf. when I was paying attention to mpg
MAC CAI-- $160 shipped--cant get that any more, $170 now.
Elect. fans-$180 shipped--Lincoln ls fans with a controller and a 50amp fuse
G. headers-$175 shipped--I dont know if they helped any, just part of the list


Not only will they up the mpg, but give you quiet a bit of hp that your truck should have came from the dealer with.