Technology is taking a lot of the "driving" out of today’s cars, whether with advanced safety nannies like lane departure systems or sports cars with advanced automatic transmissions.
But one piece of burgeoning technology promises to deliver better mileage at the push of a button.
It isn't just luxury cars that have these selectable driving mode buttons. Models as plebian as the Honda Civic and Dodge Grand Caravan have fuel-saving economy modes; others, like the Nissan Altima and Honda Accord, have Sport modes.
But do EPA ratings reflect this technology?It depends.
These selectable driving modes can dial in mileage-saving economy settings alongside a Normal mode. Others have more options besides efficiency for Sport and sometimes Super-Sport modes. In turn, all can influence gas-pedal sensitivity, automatic-transmission shift patterns and steering feedback. Some Sport modes can even dial back an electronic stability system or hunker down an adaptive suspension to sharpen handling — and a number of economy programs, in turn, can restrain the air conditioning in the name of efficiency.
Such programs certainly affect real-world gas mileage. A more sensitive accelerator or kickdown-happy transmission often trades fuel efficiency for performance; relaxing those inputs with an economy mode, by contrast, guzzles less fuel and generally provides less excitement behind the wheel. The differences can be significant: In an unscientific mileage drive in 2009, we observed that driving in Sport mode could slash mileage as much as 11%.
How does the EPA take all of this into account?
"All EPA ratings are done in the Normal mode," Honda spokesman Chris Martin said of the Civic and Accord, which have Eco and Sport modes, respectively. "EPA ratings are trying to create an apples-to-apples comparison between models, which is best done in a default normal driving mode."
Honda is but one example. The EPA sent us a statement along with a 2009 policy document that said it would handle such driver-selectable systems "on a case-by-case basis." Here's how it shakes out:
The upshot? If your car stays in the mode you left it the last time you drove, chances are good the EPA window-sticker mileage reflects some or all of its driving modes. But if your car defaults back to a default mode, chances are the EPA mileage only reflects that mode. That's why those window stickers say, as always, that your mileage may vary.