I just installed cmcv delete plates and underdrive pullies last weekend and my mileage actually went up 2 mpg to 21.75. I usually average around 19.5 with a combo of city and highway.This is after doing a few burnouts and running it through the gears after the install. Oh yeah I had a Shelby GT chasing me down the freeway at 110 mph so I wasn't babying the car.

 

You're going to need it with gas hitting $3.69 a gallon for 91 octane!

 

I bet it's the underdrive pullies helping. I don't think the charge motion plates would affect fuel economy all that much. Good to know though, that might be reason enough to buy UDP's if you can squeeze a little more economy out of the car with them.

 

Yep, $3.599 today for 91 octane at ARCO.

 

Thats about what I gained........

 

I have the 3.55 gears, C&L Racer w/ tune, and UDPs. I went from 20 city to 22 city with the UDPs. Best Hwy was 27.3 MPG (downhill, wind to back, etc...). What I find is that I average 20 to 22 based on combo mileage due to driving style.

 

For heavens sake, if mileage was key you should have bought a V6. JK of course. Nice side affect from your mods bro.

 

My UDP's boosted my gas mileage by 1 - 1 1/2 mpg before I put the 4.10's in. I took a run up Ron Leonard's shop (Spydershaft) last weekend - about 120 miles round trip and actually got 20.45 mpg for the trip which included some WOT time.

 

What the heck, MPG gain?????????????
My MPG was 17 before UDP and CMDP's install. After it is 16.4!!!!!!! What gives?
My driving style is the same before and after.
Looks like you guys are running Brenspeed tunes, wonder if its my Bama tune?
Any of you guys notice a faint sucking or vacuum leak coming form the engine bay with barley tapping on the gas while driving? You really have to listen for it. I may have to revisit my install!

 

I noticed 1 1/2 to 2 mpg gain after installing my UDP's also. I told a few other GT owners it was worth the money for that reason and even for the small performance gain.

 

I was getting up to 24mpg city until I added the CMDP's. They took me down to about 21 max. So it definitely was the UDP's.

 

I was running my dyno tune and only getting 18+. Switched back to Doug's 93 tune and it went up to the 20+. Not a daily driver because of the traffic density in the DC area so it's hard to get a real good read on the MPG. But, like most of us, I didn't buy it for any economical reasons.

 

It's funny you guys should mention this. I had the same experience with my '96 and now with the '05. My gas mileage went up a little after mods in both cars. I had (and have) underdrives and tunes in both cars, so I can't say where the improvement came from. I think it might have been the tunes that just set the engine running a little more efficiently than stock.

 

silly question do I need to retune for the under drive pluuies?

 

No..............

 

I don't get it...No matter what mod I install, my mpg stays the same. Right around 14 mpg.



Maybe my next mod sitting in the garage will help...Saleen S/C

 

Hey Alex,
I may have an idea about way your gas mileage is so low. After you get that Saleen on I think your going to need a new speedo. Maybe one that goes to 200.

 

+1

 

It must be nice to legally drive super fast. Gotta love the autobahn. Man I would have thought that you had that S/C on there by now!

 

Maybe I can find a European gauge cluster so it reads 240.

Anyway, I know, you'd think I'd have the S/C in by now. But I've been to busy to mess with it, plus I had to get some other stuff for the install. I've already got the GT500 fuel pumps and gauges in. I still need to get the bung for the wideband welded in and then I'll be good to go. Track opens 19 Apr, so it'll be ready by then for sure!!!

Figured I'd just hijack your thread since I'm not doing the install yet...