jdhommert

I'm a person who actually does care what my cars get for MPG as I daily drive them and do a ton of rural/highway driving.....

Anywho

With the improvements and focus that GM has made regarding gas mileage......

DI
DOD that works very well
VVT
More aerodynamic, less lift
Went to the trouble to create an Eco mode on a 450hp car
7 speed etc
LRR tires (at least in the base?)

Now take what we already have (real world mostly)
C5s can get way more than 30 highway
C5Zs can get more than 30 highway
LS2s can get over 30
LS3s I think can still do 30 or more right?
I've even heard of some LS7 owners claim 28-30 highway, usually 28/29 on the high side

I'm thinking that on a flat long highway doing...idk 55-70... after its warmed up,got a few k miles on it, in 4cyl/eco mode that you'll be able to hit and perhaps hold 40 at least on the DIC in those conditions. Maybe I'm crazy.

Now I know its crazy to even think of making this comparison....but a Cruze eco real world people are getting even 50 in highway/rural conditions and averaging 40mpg a tank. They say you can get the 42mpg highway rating doing almost 80 or so. Totally different situation as the Cruze has a turbo, weighs less etc..but the C7 will still be more aerodynamic and be able to cruise at a much lower RPM I'm really hoping for a good 30mpg highway rating on the sticker. They'll test it in the default touring mode sadly.

So pure highway.....in a VVT 4cyl mode....with a 7th gear....in Eco mode....What do you think? Am I insane?

What are your thoughts or predictions on MPG of the C7?

indyjack18

I cant figure out your question
I would guess with all the correct variables, one could get mid 30's

LS1LT1

There will very likely be some reports of 35mpg on the highway with this new car.

ZL-1

I've been predicting 35-ish all along in a normal interstate trip with the 7-speed manual. With a little hypermileing 40 might be possible. And the base 18/19 tires are claimed to be LRR.

jdhommert

Started the thread as mainly just an open discussion about MPG and looking for people to respond to my thoughts, but basically the question I added above is what do you think the C7 will do as far as MPG. I'm mostly concerned with real world highway, but I'd love to have any kind of discussion

jdhommert

Oh wow, didn't know that. Just the base c7 has the LRR tires then

I guess I'll edit my post to add that

Will the Z51 have the same 7th gear as the base??

Dou12buyit

I am pleased to learn about the LRR tires too. I would say 35MPG.

RocketGuy3

Of all the things you listed, this is the one that I'm pretty sure would actually have a negative effect on mileage (the bolded part, at least). More downforce = more rolling resistance.

...

That said, I am betting this will be the highest EPA-rated Corvette ever. My guess would be that it'll be rated at least about 20/31/25. In that case, I could see ~35 being doable on the freeway.

If it can really do that, it would help make up for the rather disappointing power figures for me. I also definitely care about mileage, both for my sake and because I'm a bit of a tree-hugger.

LT1_E85_Corvette

I predict 40MPG+ at the right mph in 7th gear

I was getting 32 in my LS3, so DI and 4 less cylinders will net some crazy ratings

Elkwood

27 to 32 hwy.

jdhommert

Ah ya I didn't think about that regarding the lift, but that probably has almost no influence on MPG anyway.

Totally agree.

Kappa

The only problem I can see for EPA testing is that if they don't allow the car to test in Eco mode, we may not see the huge improvement at least on the sticker. I'm pretty AFM doesn't activate in the normal Tour mode.

If they allow the Corvette to use the AFM during the test, it should see 4 cylinder type mpg.

WaxWeekly

IIRC - One of the testers was quoted as saying he was getting up to high 30s. I can't find the link, but I believe he had said 38.

I expect EPA ratings of 20/30 for the base and 19/29 (weight, aero and gearing) for the Z51. I also expect that if babied on the highway we'll be able to see 36-38 with 68 MPH cruising.

My coupe got 21 around town and 30 HWY at 70 MPH. My GS lost 2 MPG across the range.

My math: I drive ~13000 miles a year and pay about $4 a gallon. Given a 20 mpg average, that's $2600 a year or ~$215 a month. I'd love to recover some of that cost. If I can get up to a 24 mpg average, it would be a 20% savings. $40 bucks a month is nothing, but I'll take $500 bucks a year over a kick in the teeth any day. I'll just need to remember to sell it to the wife in the form of nice dinner dates courtesy of my more efficient Corvette...

jdhommert

I'm pretty sure it still activates in touring

Kappa

If that's the case, it should smash the C6's numbers. Even on half the cylinders it should have more than enough torque to putt the C7 around town.

Scissors

Pure highway MPG, which is almost a best-case scenario and not representative of anything other than open-road long-distance travel, is primarily determined by aerodynamics. Pushing 25 HP in air and rolling resistance is still 25 HP even with fewer cylinders. The gain is in pumping losses in the engine, which is (IIRC) around 15% improved. Assuming the same aero losses as a C6, expect a 15% gain in MPG. From 32 MPG that would be 36.8 MPG.

Assuming the same 15% increase for city, expect a change from, say, 18 MPG to 20.7 MPG when putting around in a city (city cycle only, not mixed driving).

pewter99

does the system work while putting around town or only when up to speed/cruising? IDK???

BlueOx

Same here. IMO, if you don't get 35+ with the 7 spd manual on the freeway, you aren't trying. If you are trying and can't get that kind of mileage, GM messed up big time.

jdhommert

I think AFM works in tour mode, but the EPA doesn't ever turn any eco mode on during a test. Researched this a couple nights ago while having a MPG discussion. Default mode is touring i'm pretty sure so that's where they will test it. They should have made default mode Eco mode for the EPA tests!

Um......I disagree with what you are saying about fewer cylinders. There is a reason the most efficient cars on the highway ever are 3cyls. Yes aero is VERY important and a major factor, but it seems rather silly to say it doesn't matter how many cylinders are pushing the car and how its geared etc. If that was true what's the whole point of shutting of 4 cylinders? Why would all 4 cylinders get great mileage and V8s usually do nowhere near as good? I said above a cruze eco that is nowhere near as aerodynamic as a Vette gets 45+mpg real world at that's conservative. Vettes do about 30 at lower RPMS. Autos usually do a few mpg less than a manual....I could go on and on. Also with your 25 hp example, maybe thats all it takes to propel a car at 60mph and thats all a 4cyl has at 2k...but it's not like a Lsx car or the new LT1 will magically "retard" it self to only having 25hp at 2k so it's just as efficient. The LT1 makes 319 ft lbs at 1000 rpm. That's a good thing, not bad. That will help keep it in 4 cyl mode.Which will make a difference.

I'm literally in the middle of 5 different things and didn't spend more than 30 seconds reading your post so maybe i completely missed your point or whatever

jdhommert

Good question, I'd imagine while even holding a lower rpm/steady speed around town or at least while coasting it will still come on...and I'm thinking in eco mode it will get pretty aggressive