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you will never see a 400hp V-8 car that gets 40-50 mpg

at least not on conventional gas.

maybe on electric or natural gas, but def not on pump gas (obviously talking about the "equivalent cost" here as they are different kinds of "fuels" ie., like getting 40 miles on the same cost of electricity or natrual gas you would get for the price of a gallon of pump gas)

too much displacement, it takes a lot of air/fuel spray to fill all those cyls

Only if the person driving it looks like Pete Rose.

Direct injection,
something small on the order of 327 ci motor
small'ish twin turbo's (to minimiza lag and optimize efficiency),
a 3.23 rear gear (hot rodders can always gear it down)
6 or 7 sp manual or
7 sp auto (true dual clutch type tranny-DSG),
curb weight 3400lb,
IRS (or SRA if necessary to keep the weight down...Ford figured out how to make it handle), low cd,

This type of setup with enable you to tune it and instantly pick up 50-80rwhp (hence, aftermarket friendly), knock down crazy mpg (30+) with the efficiency of a small motor, DI, and small turbo's, and with a nice power to weight ratio, and close ratio gearing in the tranny, very quick acceleration. "think a more powerful, yet more efficient BMW 335i" in the form of a camaro.

For those that know, an JB4 335i will run 12's (picking up 60-80rwhp over stock with tune only), and those guys are still knocking down 30+mpg in crusing conditions...no reason a small LS based twin turbo DI motor in a platform in the 3400lb range couldn't do the same.

Hopefully CAFE and the EPA will be terminally ill in 2013:thumbup:

i'm betting GM debuts a true DCT transmission in the C7 and 6th Gen Camaro...

I'll take that bet...semi-official documentation of an 8-speed auto in development begs to differ....:laugh:

DCTs...at least cost-effective ones...are difficult to use in high-power applications.