I'm not an engineer by any stretch of the imagination... but anecdotally - I don't think there's a question any more. Unless some one ACTUALLY innovates. I'm not suggesting that there haven't been any innovations - some crazy cool stuff has happened in the last hundred years of cars... but I think there is only so much more you can push the current design. We the consumers are the biggest part of the problem. I could probably build a safe and reliable compact car that gets 90mpg with existing technology... but is ANYONE going to buy that car? No. because you don't get 90mpg without sacrificing power. People don't like to go 0-60 in 30 seconds... they want it in 4. Consumers want their cake and want to eat it too. We want supercar performance on 50mpg. Ain't gonna happen with the current ICE.I'm starting to wonder that maybe we're starting to see the technological limits of ICE engines