Why does this matter? Well, owing to the higher compression and the more even mixture, direct injection engines produce more power AND get better fuel economy. The higher the pressure inside the cylinder, the stronger the "pop" when the mixture ignites.
Taken to the extreme, we get the new Lexus LS, which earns EPA ratings of 19 city and 27 highway despite tipping the scales at over 4,200 pounds and being powered by a 380-horsepower 4.6-liter V8. The previous LS earned ratings of 18 and 25, respectively, despite weighing a couple hundred pounds less and having 102 fewer horses under the hood. Similarly, Volkswagen’s GTI and GLI with their 200-horse 2.0-liter turbo four and nifty DSG transmission earn ratings of 25 city and 31 highway. The old power train, which paired a 180-horsepower 1.8-liter turbo four with a five-speed automatic, managed only 22 city and 29 highway.
Only in the 2006 model year did direct injection become available in the United States in more than one or two models, and it remains far from common. But it should spread quickly over the next few years, and I suspect that in five years the majority of gasoline-powered cars will have it. So you can probably look forward to more power and better fuel economy in your next ride.