I find on mine, 4 speed. 3.36-1 gear. slightly modified 350. Good ign curve, EFI dialed in at 14.6 at cruise. very open exhaust. (Who needs mufflers). about 22 on a long run. about a thousand miles to Cairns and I went there and back in the last year.
But, ripping around the neighbourhood. Well, it's a Corvette.
I don't really drive it for mileage most of the time.
But it's heaps of fun! And yes premium petrol over here is over 8 bucks a gallon AU. Converting to US dollars, it's well over 12 bucks a gallon. it's a weekend toy.

 

bone stock 01 vortec engine. 4l80e trans. efi. 11 mpg at 55. 10 at 63. not very aerodynamic. so any corvette with the same 350 getting 10 mpg has serious fuel and/or ignition issues.

 

How about MPG on a stock 427/390? Been a looong time but it seems to have been 8MPG back in the day when I had my '68. Without my foot in it.

 

My 427/400 with correct optimized timing and a 3.08 gear got 13-14…..and that was with my foot….
Typically any old car got **** for mileage due to the pathetic timing setting dictated by the very first EPA mandates…..
Just about anything back then would pick up 30-40% in mileage just going with a performance timing curve and full manifold vacuum to the distributor can.

Jebby

 

you wouldn't think making a car pass epa numbers would make it pass more fuel, but it is absolutely the case. i guess part of it is you can't smog a car as it goes by at 60 mph...

 

If you're not averaging under 12mpg.......you're driving it wrong!!!!

 

Keep in mind that everyone drives differently. I can typically get at least 5mpg more out ov a car than even the owner can, sometimes a lot more. Even when i speed, i get decent mileage. I've not driven my Vette yet, nor have i owned a 350 since i was 17, but i would hope that any well-tuned smallblock Corvette without silly rear gears would get decent mileage... driven right.

In the last 30 years (in about as many cars), i have driven exactly one smallblock car. 78 Volare 4dr, cop 360 & 727 tranny, high gears. Bone stock and the ONLY thing i did to that car was lower it (merely by going from 26" tires to 24"). That thing got ABSURDLY good mileage. WELL into the 20's. Those later cop 360's are every bit the engine the L82 is, and i was pushing through a single exhaust with cat. Hell, i didn't even tune it. Was running well on the stock tune. EVERY single thing about that car should make it worse on gas than a 350 Corvette. Quite honestly, i expect my lower, much lighter, sleeker, Corvette to do even better... even without the 4-speed swap.

 

my 71 LS-5 TH400 3.36rear got 15 on the hwy. with a very slightly bigger crane cam and headers it still got 15. when i rebuilt it and put a comp cams 292 cam in it i was still getting 14 on the hwy. now with the Vortecpro 496 & 3.70 rear it gets uh less . . . .

Pat

 

My '78 bone stock 4 speed gets 10.5 in mixed commuter driving. 35-60 mph, through various towns to and from work, about 50 miles round trip. I'd love to see the 15 mpg it claimed when it was new. It's had the carb rebuilt, timing adjusted, etc. recently as well.

 

My 73 with all the mods gets about 17 mpg on a road trip
before the TH200R4 in got about 12 mpg
3.55 gear
Lars tuned distributor
Holley 4175 cab
Eldebrock 64 cc Heads
2-1/2” Magnaflow exhaust

 

my 75 all original gets 15 local and 22 highway

 

I agree Derek .. no reason you can get 13 to 15 and over 20 on the highway

 

If you have to worry about gas mileage you shouldn’t be buying a Corvette or likely any old classic muscle car. Especially one that is likely going to be an occasional driver. If you can’t afford the gas you have no business buying a car like this.

 

For a hobby that is increasingly parking their classics or trading them outright for modern 'muscle cars', i dont think one should be ignoring ANY reasonable reason not to drive one. I know exceedingly few 'car guys' that actually drive their classics anymore. Most ov them have a modern Mustang/Camaro/Challenger/whatever. Even the ridiculous ones like Hellcats get good mileage. Its bad enough that people get 15mpg out ov a (by comparison) anemic 350, but 10? Whats the point? At this point in time, we should be doing anything and everything to make these old cars more viable, even if its just for fun time. My 72 440 Charger got EIGHT MPG. It was a completely sorted car, except for some badly repaired suspension damage that increased rolling resistance. It wasn't slow. But for EIGHT MPG? It WAS slow. If i'm getting eight MPG, i'd better be running tens in the quarter. It literally made the car pointless to drive.

And again, as i have said, as others have said, it your 350 Corvette is getting 10mpg... well, you've got problems. Either you have an absolutely GROSSLY mismatched combo, a horrific state ov tune, serious chassis/brake problems, or you drive like a retarded 16 year old in a stolen car. SOMETHING is off. If its the latter, then fine, obviously thats your style, but if its any ov the former three, nope... not good.

NASCAR 358's get 6mpg, averaging speeds over 190mph. If you are getting similar mileage on the street you are either dumping fuel into the crankcase, or onto the ground.

 

Mr. Pale Roadster. Many of your points are valid.
Yet, could you PLEASE learn to spell a simple 2 letter word.
Of.
Yes, O. F. NOT ov.
Drives me insane that a 2 letter word can be repeatedly misspelled.
Of.

 

@68hemi, wake up on the wrong side of the bed? It's not a question of affordability. Even when gas was at $2.00/gal. I put an overdrive trans in my '71 Cutlass to get better mileage. The technology exists and I happen to drive the **** out of my car. I plan on driving it down both coasts, Rte. 66, to Crusin' the Coast, etc. It's only natural to want better mileage especially at 80 mph on the highway. Around town it is what it is, but I'd still like to do better.

 

@Pale Roader - Yeah, at some point I see a 5 speed going in.

 

F.Y.I. My bone-stock '78, L-48, M-20 4-speed, 3.36 gears with about 1/2 of emissions removed, gets an amazing 15.2 m.p.g. around town! Never drive hi-way, so don't know that. Regards, LowSporty

 

Tell you what, when the rest ov North America can spell a TWO-letter word correctly... and by that i mean the word 'to'... i'll do my best. Clearly i am doing it on purpose. Whats everyone else's excuse? We're talking pre-kindergarten level English here.

 

Thats decent. If you still have the stock exhaust then i'd be REALLY impressed! There's probably 5mpg there alone. You're already looking at around 18-20 on the highway.