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It seems like there are Corvette skeptics out there that don't think that C4 owners can get over 30+mpg in these cars. I'm talking actual figures based upon fillup and actual miles driven, not on the cars computer. Six speed manuals with a stock axle ratio of 3.45 can do it. It is knowing how to drive, but one punch of the accelerator will lower mpg quickly!
So how many have gotten actual mileage over 30 and how did you achieve it? Computer tune, driving techniques, fuel additives etc.? Share your thoughts.
In the 95 on the freeway I will get 28.8 (+/-). Keep your foot out of it. Coast on the on the long down hills in 6th.
My 85 was an automatic with 3.07's. I would get 26.6 or so on the freeway. When I dropped in the ZZ4 with SR, AFR heads and cam....believe it or not I would get 30.0 on the nose from the Bay area to Seattle (up over the mountains) and the same MPG from Bay Area to LA. Just had to keep your foot out of it and watch the instant mileage.
St. Jude Donor '10-'11-'12-'13-'14-'15-'16-'17-'19-'20-'21-'22-'23
Yep, it is possible.
My '96 LT4 on the 2006 Power Tour
Round Trip from Rolla, > Orlando, FL > Englishtown, NJ > Back to Rolla, MO
3,996 miles.
You can see a very clear pattern. Long stretches of Interstate Cruising and it is easy to get 30+ mpg.
Now look at stop #4 (Orlando, FL). This was over the course of two days of city driving with a little "stop light" fun rolled in. So, only 12 mpg then.
The best mpg was that 500 mile stretch of I-70 from Columbis, OH to St. Louis, MO on the way home.
Fairly flat and cruise set = 31.8 mpg
When I went to Bowling Green in 2003 for the 50th Anniversary celebration, I drove my '92 vert. It had a 2.73 gear and I got some really good mileage numbers. Going across country on the freeways, the group I was in tried to maintain a 75 MPH pace. Using the cruise control and running that speed, I consistently got 30 MPG. Coming home going thru Texas and Oklahoma on I-40, I saw 32 MPG running around 65 with cruise control.
Before I left on the trip, all I really did was to change spark plugs and replace plug wires.
Managed to get 27-29 on the highway a couple of times. Mileage lately has gone down till Opti just crapped out. Fresh plugs and Opti going in, so hope to be back up in the high 20's or maybe even bust 30.
It seems like there are Corvette skeptics out there that don't think that C4 owners can get over 30+mpg in these cars. I'm talking actual figures based upon fillup and actual miles driven, not on the cars computer. Six speed manuals with a stock axle ratio of 3.45 can do it. It is knowing how to drive, but one punch of the accelerator will lower mpg quickly!
So how many have gotten actual mileage over 30 and how did you achieve it? Computer tune, driving techniques, fuel additives etc.? Share your thoughts.
I've gotten over 30 on several tanks. Stock '92 LT1/6 speed. Only fuel additives were those that came in the gas, from the pump.
Best was driving to Vegas from Ridgway, CO (Telluride area). Set the cruise at 84 mph, got a hand calc'ed 32.23 mpg. Love it.
I have hit 30 quite a few times with my '94 6M. I do a lot of highway driving too. The 30's were on highway trips.
My normal commute was mostly highway (about 20 miles with 55 limit, about 25 miles with 65 limit and about 5 miles in town for about 50 miles one way). I usually set the cruise at 6 to 8 over the limit. In the summer my average was about 28.5 mpg and in the winter went down to about 26.5 to 27 mpg. If I tried to stretch mileage I could do better, but that wouldn't be my normal driving.
My '95 6M is doing pretty well and should be close to the same as my '94 was.
I also had a '87 4+3 non-Z51 4+3 (0.6 OD) and from Denver to central Illinois I got 30.1 on a vacation trip of about 1000 miles.
I also had an '88 A4 (2.59 axle) and it was close, but not quite as good. I hit 30 with it a couple times, but it was rare.
The LT5 with its unique throttle body can get 27-30 mpg. It has a single small throttle plate in the center that it runs on when just cruising and two large plates to make HP.
I got 27.5 last Friday on a 450 mile trip, that included some city driving, a squack of the tries and shifting aggressively some. 6speed here with 3.45 gears. I was gonna try to get 30 or more on Labor Day weekend, not sure exactly where I'm going but probably the Bowling Green area again, Horse Cave most likely.
The 86 coupe with a 4+3 manual got over 30 but mostly high 28 or so.
My 87 convertible I have now gets about 13 to 15 mostly with 20mpg tops. That's with a 383 stroker, automatic and 3.73 gears. While it lacks mpg of my 86 it will blow the doors off the 86 I had
We Gone, I wonder what a throttle body like you mention on the zr1 would do if they made one like that for the LT1 and4?
I could be wrong, but I'm not convinced the size of the throttle plates have as much to do with mpg as perhaps they do with drivability, especially due to closed loop/cruise.. I think that is the reason my mileage didn't change (far as I can tell) after completing the 500+ hp "package" which retained the stock cams* and throttle body.
*The cams were re-phased, however...
For the way I drive (speeds) and the terrain combo of flat and hilly, my Z has done 28.x, generally at about 75 mph (cruise is set, diff = 3.45 gear). It depends on wind speed and direction too; especially a strong head or tail wind.
My 95 LT1 Vette did touch 30.5 at 75 mph cruise, crossing NE. Loved that car and the LT1/M6 combo. (Wish I had kept too instead of trading it away.)
The LT5 with its unique throttle body can get 27-30 mpg. It has a single small throttle plate in the center that it runs on when just cruising and two large plates to make HP.
Originally Posted by scotth48
We Gone, I wonder what a throttle body like you mention on the zr1 would do if they made one like that for the LT1 and4?
Originally Posted by Paul Workman
I'm not convinced the size of the throttle plates have as much to do with mpg as perhaps they do with drivability
Paul is right. The TB size/shape/design etc has little to nothing to do w/fuel economy. It has more to do w/managing off idle throttle response, and in the case of the ZR-1, the "Valet" feature.
The ZR-1 gets good mpg b/c it makes large tq at low RPM so can be geared accordingly. It probably doesn't typically do as well as an LT1 b/c it has more internal friction, and weighs more.
08-24-2015, 11:58 AM
MPG Skeptics
I've gotten over 30 on several tanks. Stock '92 LT1/6 speed. Only fuel additives were those that came in the gas, from the pump. 
