Sometimes we zoom down the road without knowing exactly where we are going. Then, it’s time to stop and ask for directions. When that happens on our drive to sustainable transportation strategies, we give a call to John DeCicco, senior fellow at Environmental Defense.


General Motors is applying their hybrid technology to larger, gas-guzzling vehicles. Are they on the right track by trying to improve the fuel economy of the cars and trucks which consume the most gas?

John’s Reply


One shouldn’t quibble about where automakers apply hybrid technology, or any fuel-saving technology for that matter. "Beggars shouldn’t be choosers" (one might say), given the urgent need to cut fuel consumption and greenhouse gas emissions. Moreover, there’s no point in being judgmental about the type of hybrid technology—"micro," "mild," "full," "plug-in," or whatever—that an automaker uses to boost fuel economy.

It’s also quite true that the most consumptive vehicles need improvement the most. As many readers may realize, a focus on fuel economy, as opposed to fuel consumption, can be confusing when thinking about the benefits of any fuel-saving technology. A 2 mpg gain in a 16 mpg vehicle—in guzzler territory, if you will—saves just as much fuel and cuts just as much carbon as a 9 mpg boost for a vehicle that gets 32 mpg to begin with. (Don’t believe me? Try the math, assuming the same amount of driving in each case.)

Hybrid technology, like any design feature, is best utilized in market segments and in a manner where it delivers the most value from the perspectives of both the customer base and the automaker’s capabilities and costs. Those of us calling for change from outside the industry will do well to not second-guess the particulars of technology application, or even whether a given vehicle uses some form of hybrid technology as opposed one or more of the many other ways to improve efficiency. That’s why, as I’ve written elsewhere, tax credits or other incentives targeting specific types of hybrids (or diesels, for that matter) may not be a prudent policy, compared to simply encouraging consumers to select the most efficient vehicles that meet their needs and fit their budgets.

From an environmental perspective, the bottom line for assessing any automaker’s progress is not how or even whether they bring hybrids to market, but rather how well the company cuts the average CO2 emissions rate of the entire product mix it sells from year to year. For companies that rely on sales of pickups, SUVs and other relatively consumptive light trucks, such as General Motors and Ford, improvements in these vehicles will indeed be an effective way to lower their fleet-average CO2 emissions rates.

Based in Ann Arbor, Michigan, John DeCicco is a Ph.D. mechanical engineer who specializes in automotive strategies for Environmental Defense, where he evaluates vehicle technologies and helps develop market-based policies for addressing the car-climate challenge. John was the original creator of ACEEE’s Green Book, which references for the its Gas Mileage Impact Calculator and lists of the "greenest" and "meanest" vehicles, and he has published widely-cited technical studies on automotive energy and climate issues.