Fuel Efficiency: Dependent On Internal Combustion?

Perhaps more than any other comment, the one I hear the most from readers is "when are we gonna see cars and trucks with better mileage?" Typically those comments are followed by questions about hybrids, diesels, or sometimes even electric models.

GM logo, General Motors logo
GM logo, General Motors logo

I bring this up because we are at a crossroads in the auto industry. On Friday, GM showed reporters a new engine it's developing that, in theory, will be 15% more fuel efficient. It was one of many powertrains GM showed reporters as part of an effort to change public perception GM lags foreign rivals (Toyota ) in developing new technology.

Fact is, GM and other automakers are more aggressive than ever about testing new ideas that will help us go further on gallon, and maybe someday not use gasoline at all. On paper, the promise of the technologies is remarkable.

In reality though, they are a long ways from being widely available. Why? Sometimes it's because the technology will take a long time to develop (an electrically powered car like GM's Chevy Volt). Other times it's because the widespread customer base is slow to embrace the new technology (hybrids) so the offerings are limited.

Which brings us back to trying to get more out of our standard internal combustion engine. GM and others are making progress. And for now, that's what we'll have to accept as we wait for the newer technologies to be built or more widely available.

Questions? Comments? BehindTheWheel@cnbc.com