GM: Yes, the Volt's gas engine can power the wheels

Until today, talking about whether the internal combustion engine (ICE) in the 2011 Chevrolet Volt should have a direct mechanical connection to the wheels was an interesting thought experiment. Sure, there were hints and patents that suggested that the ICE could drive the wheels, but General Motors kept saying its "extended range electric vehicle (ER-EV)" was just that: an electric car with a gasoline-powered generator on board. Guess what?

GM has now confirmed, late in the game, that the Volt can, in some situations, use the ICE to power the wheels. This came to light after Motor Trend was allowed to test the car for three long drives and discovered:

However of particular interest, when going above 70 mph in charge sustaining mode, and the generator gets coupled to the drivetrain, the gas engine participates in the motive force. GM says the engine never drives the wheels all by itself, but will participate in this particular situation in the name of efficiency, which is improved by 10 to 15 percent.

This is exactly the opposite of what GM has been saying for years – most recently in June, when GM spokesman Rob Peterson told AutoblogGreen that there was no mechanism in the Volt to drive the wheels even if the engineers wanted too. Or, at least, that's what we heard. Peterson told AutoblogGreen today that the "news":

is consistent with everything we've said to date. The new "news" is that we can tell the complete story as our key patent has been allowed by the US patent office. The Volt is an electric vehicle with extended range as the Volt has full battery electric performance at all speeds when there is charge in the battery.

Click past the jump for more.

[Sources: General Motors, Translogic, Motor Trend, Green Car Advisor, The Car Connection, Popular Mechanics]

So, from what we know now, the Voltec drivetrain has a single planetary gearset, a pair of electric motors and, of course, the gas engine. The systems central sun gear gets power from the 149 horsepower electric motor at all times, while an outer ring gear gets power from the engine or the smaller electric motor when needed. The planet carrier then sends power, from whatever source, to the wheels. GM global vehicle chief powertrain engineer Pamela Fletcher told The Car Connection that the two-motor powertrain gives the Volt three more miles of electric-only range than would otherwise be possible.

Like we've said before, it makes sense for the Volt's engineers to design the powertrain to be the most efficient they can, and if they think that some gasoline assistance will help buyers choose this partially electric car, then that's fine. Labels are just labels. But what will GM's marketing arm, that's been so preoccupied with saying the Volt is an ER-EV that's totally different from all other cars out there, do now that we know the Volt is pretty much a plug-in Prius with a bigger battery pack? For what it's worth, some of the first real-world Volt tests are showing around 33 miles in EV-only mode, compared to the plug-in Prius' 13 or so. Thanks to David M. for the tip!