rmriggin: direct-injection has really only recently become feasible, since it requires very accurate injection patterns to create the proper charge stratification. Mazda has been researching it and rumor has it the next-generation Renesis may be direct-injected. Direct-injection actually works wonders on rotaries in particular due to the turbulence in the combustion chamber. I read somewhere (I could find you the link if rx7club's lounge weren't currently missing) that direct-injection can yield a 15-20% increase in fuel economy and similar increases in power over conventional fuel-injection on rotaries.



FC/DC: Well, I'm a little skeptical about hydrogen as a fuel. Why? The energy density sucks. You can't get around the laws of physics. Even liquefied, hydrogen's energy density by volume is around a quarter what gasoline's is (I won't even go into exactly how feasible storing liquefied hydrogen in a car is, nor the amount of energy the liquefication process takes). This means that range is low, power is down (the Hydrogen RE RX-8 makes less than 120 HP on hydrogen, and then only for 62 miles), and filling up and storing the fuel is difficult. Also, here's a fun link for you to ponder: http://en.wikipedia.org/wiki/Hydrogen_embrittlement



Here's my version of this thread: "Why buy gas? Go electric." Sure, the batteries are bulky right now, but there has been some really impressive stuff being shown off recently with ultracapacitors and whatnot. It's cleaner than hydrogen, no high-pressure storage tanks, ridiculous and quiet power, better range, and much, much higher overall energy-delivery efficiency. And the infrastructure is already there: just plug it in at the end of the day and you'll be charged up and ready to go in a few hours.