New horsepower from smaller engines
I read an article in the USA Today that talked about Detroit’s new strategy for increasing the mileage ratings from their fleet: direct fuel injection and turbo chargers. Turbo charges are not new, of course, they’ve been around for years. But they quote some interesting numbers. By using a smaller engine with more push, they can make the overall car lighter. And of course a horsepower to weight ratio is an important factor to consider. The best part is that these two technologies can be used together and they have a better ROI than hybrids do. And they don’t have the messy chemical batteries to deal with.
For example, the 2008 HHR SS will get 260HP from a turbo-charged four cylinder engine. The Lincoln MKS with a twin-turbo 3.5L V6 will generate 340HP! That’s almost as much as my 5.7L LS1! 
I don’t know what “direct fuel injection” is, yet, and I’ll have to read up on that. But the numbers are compelling:
Adding direct injection + turbos to an engine: $1000 per vehicle
Adding hybrid gas+electric technology to an engine: $4000 for gas, $3000 for diesel
ROI: Between two and three years for average drivers, compared to seven years for diesels and 11-12 years for gas+electric hybrids.
The article goes on to mention that making smaller engines perform larger is the new trend, as opposed to making larger engines perform smaller with weird strategies like deactivating cylinders and so on. Dodge makes a V8 Hemi for their trucks now that will turn itself into a 4 cyl engine during low-load situations. I think I like the idea of the engine working all the time, with an extra boost coming from turbos when you need it. The turbo-diesel in my Cummins sure does a great job of moving my truck down the road. 