Just got back from a trip and discovered something that making me think ...

Our '99 SS convertible, basically stock, 4.10 gears and FTRA ... averages 23 - 25 MPG on road trips .... (I log every fill on every vehicle) ... 3650 lbs, 300+ HP & TQ

Our newly acquired '07 NA Solstice after 6,500 miles ... all road trips ... is getting 26 - 27 MPG. 2820 lbs, 170ish HP & TQ.

I'm not sure what I'm missing here but I'm now far less concerned about fuel mileage for the V8 5th gen than I was a couple of months ago.

 

I want to say the Solstice is roughly 300 pounds heavier than that, but point taken....

 

Oops! Checked my notes .... 2820 ... Sorry & nice catch.

 

That's really good with 4.10 gears.
Kuddos on the Solstice!(envious)
I still have too many kids home for a 2 seater...
I hit 30.2 mpg in my Venture LS/ext on the interstate a couple of days ago, at a little over 3800 lbs with a 3400v6, empty except for me ...most of the time I'm in the 27-29mpg range.
And I've still got this annoying miss at 1/2 throttle of more.

 

Curious to know what rpm are you turning in each at the same road speed....

My M6, C5 turns around 1500 rpm at 70 mph....and I think most 4 cylinder cars are turnng at least twice that....so approx. the same number of cylinders fired per mile....yet less weight to make up the slight mpg advantage.

Yup, I'll keep my V8, thanks.

BTW, I got around 32 mpg driving home the 1650 miles from SLC to Indy.

 

Roughly 50% higher revs with the 4.

Interesting comparo right from GM's website ...

M6 LS3 'vette 16/26
M5 2.4 Solstice 19/25

In a nutshell .... torque rules

 

Nice. Now take a look at the in-town gas mileage. Corvettes and Camaros get great mileage on the highway cuz they're aerodynamic, weight plays very little into fuel economy at highways speeds....solstice has a higher CE of drag than the vette (don't remember offhand what the camaro's is)

The camaro's fuel economy in town is worse than the vettes because it's a few hundred pounds heavier...the solstice's is slightly better because it's about 200 pounds lighter.

Engines are getting so economical nowadays that with proper gearing and keeping your foot out of it, everything that isn't shaped like a barn door gets pretty comparable mileage....you get a few MPG benefit in the city from losing a few hundred pounds, a few MPG benefit from using something like direct injection, a few MPG benefit from a manual trans, etc.

 

the 4th gen's cd isnt that great from what i remember.. i dont know the specific number, but i know the 3rd gen had a better cd believe it or not