I liked my reply to a post so much I decided to turn it into a How To. This post is brought to you by Scotch Ale, made by your friends and mine at Depot Street Brewing. So dark, not even light can escape (not their official motto, but that's how I've been pitching it). DISCLAIMER: I have a tendency to be brutally honest (especially when I've been drinking). Some people may take it the wrong way, but remember, it's nothing personal, I'm just an ass (especially when I've been drinking). Most manufacturers have already done everything they can to improve your MPG. These days, it's a great selling point. Translation: you will sell more vehicles if they have better fuel economy. They only limiting factor are those bastards at the EPA and their emission standards. There are 6 things you can do to improve you fuel economy: #1 Change your driving habits. Slowly accelerate from stops, don't accelerate uphill, coast downhill as much as possible, draft, and don’t go above 60 mph. #2 Increase your airflow by adding an aftermarket intake and exhaust (with mandrel bends). (There isn't much cost benefit here, MPG increase is minimal and parts aren't cheap). This will give you a slightly leaner air/fuel ratio (ideal is 17:1). This ensures there is enough oxygen present to achieve as close to 100% combustion as possible. There will be an increase in H20, CO2 emissions along with NOx (NO, NO2 and N2O), and a decrease in non-combusted hydrocarbon emissions. Any change will be minimal and SHOULDN"T (but might) affect emission tests. An increase in air also increases the number of particles you let into the engine, decreasing engine life. Again the effects are minimal. #3 Add an underdrive pulley. Basically, this robs power from other components on the drive belt and delivers it to the engine. Those components include: your A/C (so it won't cool as well), power steering, and your alternator (so your battery won't recharge as quickly). Not very cost effective and you gains will be minimal. The pros might not outweigh the cons if you like your A/C or you pull a lot of current. #4 Improve your aerodynamics. Lower the front end and spray your entire vehicle with Teflon. You chose the wrong vehicle for aerodynamics, and it's not a very cost effective solution. #5 Lose some weight. Don't carry around unnecessary weight. You lose 1% economy for every 100 pounds. Go on a diet, take a dump, whatever it takes to drop a few pounds (pun intended). For more extreme results Lose the A/C compressor, radio, roof rack, spare tire and jack, all the seats (except the driver's seat), and all of your interior molding and upholstery. You could probably eliminate 250 pounds and gain .5 mpg efficiency. But think of all the money you'd make selling parts of eBay! 6 Move to sea level, or below (stay above the water please). You lose 3%-4% economy for every 1000 feet you are above sea level (unless you have a supercharger or turbocharger to cram more air in). I'd like to thank my friends Copy & Paste, Microsoft Word, SpellChecker and alcohol, the cause of...and solution to, all of life's problems.