I know for a fact that going to 2.73s from 3.55/3.73 on a Crown Vic (4.6L 2V / 4R70W) will result in a gain of up to 10 MPG on the highway, namely because the engine RPMs are kept below 2000 RPM at 80 MPH.
My 07 GT gets about 23-25 MPG on the highway. I would like to see close to 30 MPG and the hit in performance is not an issue. This way I can have both a 300 hp V8 and gas mileage that rivals most 4-banger FWD cars.
Actually, those gears that (numerically) lower would be taller gears. Shorter gears would be moving up to 3.73 or 4.10.with gears that short, off the line you'll be slow. i never have my rpms below 2000, the engine is straining to have any accelleration w/ that low of rpm's. and if you do run the 1/4 mile or do a 0-60 test it's gonna suck. i hate to be a hater on your thread, but my mazda doesnt even get 25 mpgs , and my GT gets 12-13 mpgs, but that's ok w/ me i didnt get the GT for mpgs anyways. if you do put in 2.73's you can forget about the 1/4 mile bc it wont even be worth it to run down the track. having to shift later isnt a plus, its a minus bc you're accellerating slower, i.e. trap speed will be down. sure you'll have better economy, but performance will be worse.
Actually, those gears that (numerically) lower would be taller gears. Shorter gears would be moving up to 3.73 or 4.10.
Well I always shift at or below 2k RPM with my GT, and I frequently lug the engine around the city. I never understood why people NEED to run the engine at 3000+ RPM with a manual.