Not exactly the same. I believe the block is generally the same, but the sedans version is supposedly different and has like 20 less HP and TQ as a result. I'm not sure of the effect of those mechanical differences on fuel economy, but the transmissions are the same between the 2 cars(not sure about the AWD one though, if that's what your sister has).

I bet your Z28 Camaro probably got better gas milleage than a G35 does, if it was a manual trans. Those F-Bodies are geared soo tall and have soo much torque that you can really loaf around in them and get good milleage at high speed... particularly on the highway by coasting at 80'ish MPH and be doing 2K RPM's. G35's in 6th gear spin about 3K RPM's at just around 80 MPH.. so they aren't exactly geared to loaf on the highway like some cars can.

 

yeah thats true, if I loafed around in the Z it would easily get 27-29 highway mpg. But it had a 3.73 gear. Though I did search around for the right trans, got my hands on a borg warner out of a 94 that has the super tall 6th gear with an 0.50 ratio lol. When the car was an auto it was lucky to get 23 highway though!

Gas mileage isnt really the main concern though. truck values are going down fast and are only gonna get worse as gas prices keep going up, as well as when the new fuels start coming in. Part of me feels like the infiniti will hold its value through all of this better than a lifted silverado is going to. (Re-sale is my big concern right now)

While were on gas mileage though, what is the best aftermarket exhaust available? (seeing as they all claim higher gas mileage but we all know it goes down cause you wanna hear the sound of that sweetly tuned engine haha)

 

If you do some research, you'll see that most aftermarket exhausts will yield just about the same in terms of fuel economy and performance on a G35... it's really just a matter of sound preference(primarily), appearance, and price.

 

'03 was first year - usually you should avoid those as they work out bugs/kinks after the first model year. '04 is what I would go for; has the best taillights still and, if the person who bought it originally sprung, the Brembos!