You need to do some research before calling me or anyone else a liar. I don't need to make up lies to prove a point; many C5 owners have reported similar MPG. Go look it up; it's obvious you haven't and are basing your erroneous assumption on your own pitiful showing.

Hell, I even provided a picture. What more do you want?

 

HotRodMomma-

Congrats on the new Vette - - hope it gives you miles of trouble free enjoyment. This forum can be lots of fun as long as you don't take it too seriously!

I chuckled at the question "why would I?" (run higher octane) - - we do a mix of around town and on the road. Over the course of owning a dozen Corvttes and another dozen muscle cars and working for a big oil company for more than 15 years- it is my opinion that the cars run better on higher octane.

Certainly, there can be other factors but that's my opinion. Others have theirs- ain't it a wonderful country.

The only time I've hit 30 was on a fuel miser's rally with a C3-`73 - high air pressure in the tires, leaned things out and never hit two grand on the tach - - and into 4th as fast as we could-- coasted every downhill.

The C5 and C6s both will do upper 20's coming down the hill back to Phoenix from the high country- the car's calculations seem a bit fictional- but I assume that's by design.

My Lexus will do about 1.5mpg better on 93 than 87 on the same trip to Tucson and back. Noting scientific- just my opinion and since I'm paying the bills, I'll probably continue.

Your cars - - -your call.

 

I run premium. The stations vary from 91 to 93 octane, but most around here are 92 or 93.

I can also support the mileage claims. Mine does great. My '99 6-speed window sticker shows 28 mpg highway and I do better than that. The EPA web site shows that the '99 A4 gets 25 mpg highway.

I took a 1700 mile trip this summer to the corvette museum and the tail of the dragon. There was quite a bit of lower gear "playing". The DIC for the whole trip showed 32 mpg average. Comparing with the number of gallons and miles driven I got 30 mpg. The DIC on mine is a little optimistic but the car does great.

I also tried to check the best I could do for mileage. I had to run for some parts in two different cities and so I went south abou 50 miles to the first parts place and back, then I went Northwest about 50 miles to the second place and back. I was setting the cruise at the limit which was quite a bit of 55 mph and some construction at 45 mph on the NW trip, and 55 mph and 65 mph on the South trip. I was driving very gently and even coasted down a few hills. The DIC showed 37.7 mpg and at the fill up it was 36.2 mpg for over 200 miles.

In short they can do great on mileage. They do better on the highway than my 4 cylinder 5 speed S10.

 

Its a shame that you just can't get through to those so mentally challenged that they think they can accuse people of lying, and think its ok. But when someone with automotive credentials tries to take the time to help them, explain to them like they were an 8 year old, they just fall back on their illiteracy They then call the education offered as a personal attack and cry foul.
Bill aka ET

incidentally C3 did not have an over drive gear ( less than 1:1 ) not one !
A C5 has two overdrive gears. The main focus was getting past the gas guzzler tax. Which we did and fount to be in compliance with DOT regulations.
why do people want to compare cars from the 60's and seventies to a C5?
The C5 was a benchmark design both in technology and aesthetic design. We designed active handling into the car 15 years ago and here today there are still cars almost 15 years later that's still don't use it.
WE were the first to design an engine that benchmarked at 200,000 miles. There are still manufacturers that don't test their engine designs to 200K.
When we designed the OLM system we made it so good that 3 years after the original design, found it to be better than we expected because field testing over three years showed we could push the baseline from 10,000 miles to 15,000.
IM amazed that so many people come to this forum and bitch about it no matter how good it actually is.
Its a sports car that makes over 350 HP and can get 26 miles to the gallon.
Lets go back to the 60's and a 283 270 HP corvette. that got 8 miles city and 15 miles highway.
forty years later add almost 100 horse power and double the fuel economy.

 

With a tune 93 is a must. bp or costco 93 all the time. For a few dollars more I don't understand why not. This battle will rage on & on. I like what I'm doing and I'm sure they like what they are doing. Also with a tune they tell you your mpg will rise 3 mpg. and I do believe road conditions can make a difference in mpg. evil twin makes a lot of valid points be leave it or not.

 

Thank you for validating my points. its nice that you can do this and put aside my engineering degree and my forty years of automotive engineering tenure.

 

Easy big guy I'm on your side.

 

Chevron 93 in Atlanta. When I'm in NC I use any premium thats ethanol free in the Corvettes and Harley

 

Yep, same here. Always run octane. The first time I saw over 31 MPG on a cross country trip (31.67 to be exact) I was shocked.

 

Where in NC are you finding ethanol free gas?

 

When my car was stock it would get 24-25 on the highway on 91. Supercharged it gets 22 and 14 if I don't push the go peddle too often. I run meth injection over 2 lbs. so I guess I'm not answering the OP's question.

 

Mobil 93 ( or Hess super in a pinch )

 

 

The owner's manual recommends premium, but I have run into situations where premium was not available and have run 89 octane gas in the car. I just did not drive the car as hard until I could refill with premium. For the extra 20 cents a gallon for premium, I will pay for the higher octane gas.

And when I had a six speed car, I did attain better than 30 mpg on occasion. It was not a consistent number as the conditions always changed (hills, wind, traffic, etc.) but still got better than the EPA rating. With my A4 car, I usually get between 26-27 mpg on the highway which is still better than the EPA rating.

 

93 octane from Sunoco. I add a bottle of Techron once in a while since no Chevron station around.

 

comes up a lot...what cruiser said above is about it. You can run lower but youre actually submitting the drive train to a little knock. the sensors retard the timing when they see knock...not before....its just fast enough that you don't see it.

 

Corvette_Ed made a claim of 31mpg at 75-80, but he's in Dallas. I'd love to be drivin' around Dallas; passed through several times and I recall it to be mostly flat and concrete. Around here I gotta fight to keep above 25 (hand-calculated).

I got a hand-calculated 27.4 for ~2,000 miles from Biloxi, MS to Herndon, VA. Lots of rough asphalted (and I mean, "just like you'd figure poor states to pave" *rough*) rolling hills and long pulls; 4x I had it WOT commencing at ~60/65 to > 90 (once to 110mph). Most of it was at 75mph, but I leaned on it when I had a scout. I can believe 30mpg on flatter concrete at a steady pace. I'm still waiting eagerly to take my first trip on I-10 all the way from Biloxi to San Diego to see what this Z06 can really do with a tank of gas in open country.

When I first bought the Vette, I tried regular then mid-grade, too, before settling on premium. With a mixture of "half-and-half" (89 & 93 octane) the car behaves predictably, but gas mileage is down to at least 23+; once in a while WOT up a hill with half-and-half 89 & 93 will cause knocking, so after two tanks' worth of experimenting, I gave up on cheapin' out. It's Chevron premium only now. Prolly costs me an extra $150-225 a year. That's a pretty fair trade for better performance and at least 8% better mpg.

 

I have a friend who made a trip to Oklahoma this past summer who checked his mpg both ways. He actually found that by doing it the old fashioned way his mileage was slightly better than his display indicated.

 

93 or push

 

Please don't interpret this as a personal thing, but that line of reasoning would lead one to believe that you pick up four mpg for every ten mph you drop.....so that would make 51 mpg at 20 mph Correct?

If you say that that's not true because the cars gearing would be lugging and other factors would suggest the best mpg would be at a higher speed . . .you re half way down that slippery slope

I cant relate the physics, or the "optimum" mph/rpm for gas mileage off the top of my head . . .but I can tell you . . .that in my personal experience, my 2001 A4 with a wideband street tune, blackwing and catbacks would routinely get 30 mpg on 93 octane at 65 or so on long straight runs down to the Jersey Shore.

See what I did there ?
"In my experience . . ."
pretty nifty expression....no?