[aerohead]

superchow,is your driving urban,or highway,or a mix?------If your going to "cheat",I think it would be easier on the highway than around town.Anytime you're in traffic,driveability issues will be an issue.---------- You might see 150-mpg at a constant 35-mph with a Pogue vapor carburetor(yeah they're real!),but they can't handle throttling.-------------------- The dry ice cooling you mention,is it for race cars compensating for heat-of-compression do to superchargers or turbochargers? If so,I suspect the fuel line is snaking through a "cool-can",which is a heat-exchanger type device filled with ice water,and along with inter-coolers,helps bring the charge temp down for better density (more charge more horsepower).---------------------- Modern electronic fuel injection attempts to balance MPG and driveability,with high sampling rates,and tremendous internal "look-up" menu scenarios,to anticipate conditions the car might experience.---------------- If you throw the ECM a curve-ball,by way of bogus input from sensors "seeing" artificial environments( CO2 ) it just may not have a fuzzy logic to make the best of all possible operating regimes.There's a lot of ROM in there.