the 1M. it's a hell of a lot lighter but has the same horsepower, which means the acceleration is a lot better. aside from that, the M cars have heavy-duty suspension and outstanding chassis which allows for amazing handling. the G37 is made primarily for luxury, it's heavy as hell and just not really good for anything aside from looking cool. if you're looking for a real sportscar, you have plenty of better options than either of these(especially considering that a lot of dealerships are severely overcharging for any available 1M.)