Nashville Mustang GT. The odds are against me.

[Floordford]

Hey guys and gals. Im new to being registered here but have been searching the threads for info for quite a while. Im fighting an up hill battle. Not that I don't look forward to the challenge. I drive a 2000 Mustang GT with alot of go fast mods. Heads, full K&N intake, 75mm throttle body, long tube headers, tune, lowered. Your average bolt on GT. Im starting to et more interested in seeing how much fuel this car can sip. I recently came from Townsend, TN to Nashville, TN and got 33.3mpg at 60mph. Its a 5 speed manual with a 3.73 rear end gear.

I look forward to the interchange of knowledge.

[cleanspeed1]

If you pulled that number and can repeat it, you're doing fine. Get a Scangauge on that thing if you haven't done so, and drive by that for a while so you can baseline the car. Look at the hypermiling tips and work on your driving style first. Don't even mess with the mechanics on the car yet. Put together a log and track the mpg.

It looks like you put together a winner.

Gearing will make the biggest difference, but you didn't say whether or not you did the cams also with the heads or running stock sticks. No since dropping the final drive down if it pulls you out of the powerband, making the horse run like a dog.

If you still want to keep the fun factor with the car, consider putting a 6 speed in it, keep the 3.73s, and program an economy tune to go along with the performance tune you already have since it works well.

[Floordford]

No cams. The valve train is also stock. Because I thought heads needed all new valve guides and seals, so while it was all out I had them ported and polished.

My car started off as a 4 speed auto and I just recently made it 5 speed manual. I also have a 13lb lightweight flywheel (stock is 26lb), stage 1 McLeod clutch, Steeda Tri-Ax short throw shifter, and an aluminum driveshaft. I say all that because I probably wont go 6 speed just because of the cost. Seeing how I just swapped all that stuff within the year.

Some mods I wanted to do were belly pan even if its not a full one. Maybe one that extends back to the firewall. Side mirror delete and convex mirrors mounted inboard. Front grille block off. Lexan fog light covers much like the modified Metros run. Possibly a cowl hood because my hood has the 2001-2004 hood scoop.

[cleanspeed1]

That sounds good, and you are on the right track. Since you are running the stock cams, and you did all that work ahead of the rear axle, I guess it will come down to how far you want to go with the mpg, and if you want to give up some of the acceleration to get it.

Good thing you have an 8.8 rearend.

You could go all in and drop a 2.73 to 3.08 ring and pinion in or if you still have the stock automatic spec ( 3.27 ) gears, reinstall them. Slowing the engine down is the name of the game.

The aero mods will help, but if the gearing isn't changed to go along with the drag reduction, you won't take full advantage of it.

Have you done synthetics front to back on her?

[Floordford]

Yeah, Mobil 1 in the engine always. I dont use synthetic in the transmission on purpose though. Synthetic in my transmission wont let the syncros speed up fast enough. So I use the factory recommended Mercon 5.

And ive always wanted to see back to back testing on the gear change thing. While it may benefit a vehicle on the highway I would think it would hurt MPGs more in city. You'll have to push the pedal harder to get it to move because the RPMs are lower. And most engines make less horsepower the lower you go in the RPM band. And by needing to use more power to get going it might hurt a car in stop and go traffic. I do jump gears sometimes though. 1-3-4-5 or 1-2-4-5.

[cleanspeed1]

It depends on the combination. Do a search here on the Metro XFi and the regular Metro and look at the differences. If the combination is tuned right to take into account the gear change, the mileage will get better. Since the Mustang at some point with the 4.6 had something like 3.08 to 3.27 gears from the factory, it shouldn't be too much of a stretch.

It's all a compromise.

[Floordford]

Yeah my stock gears were 3.27. I think some of the older Fox bodies ran a 3.08 and my old 89 GT came with a 2.73.

[blade]

welcome to em