Currently running a 2000 Ram 1500 SLT Laramie EXT CAB with a 318 and Auto trans. Tires are 245/75/R15 on BFG Rubber. Stock replacement K&N Filter in the stock Airbox, and a Magnaflow 2.25 inch cat back dual exhaust. I have synthetic fluids in the drivetrain and 10W30 Amsoil in the old 318. The truck currently has about 105,000 miles on it. My problem is that I dont get more than 12 MPG in the city and 18 on the highway. Now im sure this is much better than most get, especially those with the larger 360's. Since im going to be replacing my plugs here soon, I was wondering what plugs have proven to be the best for fuel economy on the 318. I currently am running Autolite Iridium plugs in the truck on stock 7mm wires. Should I try another brand? I have heard good reviews about the E3 Diamondfire plugs too, thinkin about giving those a try.

 

I am running the bosch supers, not sure what is so 'super' about them.... copper core plugs, no funky esoteric metals, etc. Runs great. haven't gauged mileage with 'em yet, but, I got about 9 or so around town....... and a high of 18 on long drives with the old plugs. Champions.... that were so ash fouled, i couldn't see the center electrodes any more. (yes, I burn a fair amount of oil.)

 

I run Champion copper plugs in my 360. I fill up after every 330 miles as my gas gauge is busted. Doing the math, I went 330 miles and put in 20 gallons which works out to around 16mpg average.

I run mostly highway @ 65mph. City driving is limited to maybe 10 miles a tank (1/4 mile off freeway to my house).