Chronicle

iTrader: (7)

Okay, I recently got a 99' Trans AM (M6) and I was saying that I wanted to see if I could get 30 MPG on it. One of my co-workers (who owns a foxbody mustang) was firm in telling me that it is impossible to get 30 MPG on a V8. Do you think my goal is feasible? If so, what should I do (outside of driving habits, since I already drive very conservatively)?

mglooper

iTrader: (5)

some members here ecspecially the ones with M6's have been known to get 30 mpg highway already. how close are you to achieving 30mpg already? things like the ram air kit will help or get a good tuner.

Chronicle

iTrader: (7)

I don't have a Ram Air kit. Everything is stock except for the air filter and the intake lid. I'm not sure how much MPG I get currently, but I plan on getting one of those MPG scanners for my car.

trackbird

iTrader: (4)

I left Columbus, Ohio for vacation in my 2002 Z28 M6 (about 2 years ago). I was in some traffic going out of town (65-80 mph) for about 60 miles. Once the traffic cleared up, I set the cruise control at 80 mph. I had two people in the car and a couple suitcases. When I got to Morgantown, WV (over 200 miles away) I filled up. I got 29.5 mpg for that trip and that included a few 8% grades that are a mile or so long.

That car had stock everything (no bolt ons), the MAF was descreened (which I probably wouldn't do again) and it was lowered (H&R springs/Koni DA's) which helps frontal area slightly. Stock manifolds, 3.42 gears, a K&N filter and not much else.

It's absolutely possible. I wasn't driving for mileage, I was driving to get somewhere in a bit of a hurry and I still got that close.

Your results may vary.

Chronicle

iTrader: (7)

That's awesome. I hope I can get as good mileage as that.

99ssleeper

iTrader: (98)

my dad and i took a trip from minnesota to indiana in his 98 ss m6 convertible. averaged 31 mpg with the a/c on. it's definately possible.

veee8

iTrader: (40)

I once logged 28 mpg with a lean highway tune with my old 420 rwhp LT4, A4 with 3.42's. Average 75 mph or so. I also tuned my buddies 02 SS vert A4, w/ 3.73's to get 28-29 on the highway. Really wasn't going after mileage, and might have been able to squeeze a little more out of it.

Reject

iTrader: (24)

driving alittle slower on cruise speeds would help to like 60 mph

GMTECH4

before heads and cam i got 30mpg highway easy and i got even more after mpg after header install. i only had lid, magnaflow exhaust, and ported throttle body no tune

Big-K-Performance

iTrader: (1)

Before I bolted up the blower I got 31 MPG.

distortion_69

iTrader: (20)

28-29mpg measured many times on extremely long road trips. I've never seen over 30, but with a few bolt-ons, some weight reduction, and wind resistance mods I'd think it'd be easy as hell to get nicely into the 30's.

I think raising your compression could be beneficial (side by side with a tune).

brad8266

iTrader: (23)

I got over 30 MPG when i was stock.

Even now with my head/cam/bolton car that is over 450HP I still get 27MPG on the highway.

duece_bigalo01

iTrader: (6)

I have a head/cam/bolton 01 SS and got 30mpg on a trip to NC from MO.now that was with no ac on and cruising around 70-75. M6 by the way.

99ssleeper

iTrader: (98)

Just got 26mpg yesterday on a short hwy road trip. This is with 4.10s, Longtubes, and 36# GM injectors with a computer that's tuned for SVO 30#...that included a little hwy run against a GN pushing ~22psi...that didnt work out so well, lol.

ChevyThunder17

iTrader: (48)

There are plenty of Corvettes out there seeing over 30 MPG, F-bodies are a little heavier and not as aerodynamic, so you don't always see 30+. That doesn't mean that you never do.

Just because Ford only sees that sort of gas mileage on it's typical flat-bed ride to the mechanic doesn't mean that us GM folks don't.

Get yourself a lid, perhaps a catback exhaust, and a good tuner or your own HP Tuners interface and start tuning.

sreve

iTrader: (3)

i have noticed a sweet spot at about 2300rpm 80mph on a 3:23 car. seems to do real well there always stay in 4th tcc lock up.
i have been using this logic to think going to a 3:42s may actually help mpgs on an a4 cars lowering that spot to something closer to leagal.

TAQuickness

iTrader: (28)

Your driving habits are the single biggest, and free, influence on fuel economy. Once you get that down, there are a few things you can tweak in the tune for better economy. Other easy things that can help are free flowing intake and exhuast systems, and weight and drag reduction. After that you can go after the engine internals as well.

30+ MPG from an LS1 powered car is definately doable, but keep in mind there is a point of deminishing returns. Going from 28 to 30 MPG is ~7% gain. If you were to spend $500 to achieve this gain, it would take ~52k miles @ $4/gallon to recover you cost.

TAQuickness

iTrader: (28)

For ***** and grins I've attached a screen shot of the spreadsheet I use to decide if an economy mod is worth it. In this instance I was toying with the idea of replacing my 17 mpg truck with a 45 mpg Hybrid.

99ssleeper

iTrader: (98)

Lately I've been skipping gears just to see if it will make a difference (yes I do have cags disabled). I'll take off in first then shift to 3rd around 20, then shift to 6th around 40. With the 4.10s it doesnt lug the engine too bad, never really dops below 11-1200 rpm.

Josh@MASPORT

iTrader: (3)

put some 27+inch tires, lean it out and 31mpg should be a piece of cake