VW’s Passat BlueMotion concept proves the Germans aren’t wholly diesel-obsessed

There are lots of ways to make a car fuel-efficient: An automaker can use a hybrid drivetrain or it can use a diesel engine. Or if it’s VW: good old-fashioned German technical wizardry. The Passat BlueMotion Concept, debuting at the Detroit Auto Show, shows just how far you can take efficiency with a plain-Jane gas engine.

The Passat Blue Motion manages a very impressive 42 highway mpg. That’s better than you get from a lot of hybrids, and remember this is an ordinary midsized sedan. So how did Klaus and Hildegard manage it?

This Passat uses a 150-horsepower 184 pound-feet of torque 1.4-liter TSI engine with direct injection and a turbo. This is pretty good, but hardly enough to take it to a Prius. So to amp up the efficiency, VW used cylinder deactivation. When you only use light throttle the valvetrain to cylinders two and three shut down leaving you with a tiny two cylinder that sips gasoline like the Queen drinking tea.

Because deactivating things was so fun, the engineering team also decided to create a system that disconnects the engine from the drivetrain as soon as the driver takes his or her foot off of the throttle. This reduces the rolling resistance to an absolute minimum, and means that you may well be able to coast for days.

Throw in a start/stop system, which allows the engine to stop at traffic lights or in congestion, and a fancy double-clutch automatic transmission and you have a large family car that is more efficient than most subcompacts.

Right now this remains a concept, and VW won’t say if it plans on putting it into production. My guess is that it will, as VW’s other BlueMotion products have met with a fair amount of success in the world market.

 Even if the Passat Blue Motion never sees the showroom floor, the technology used in it will. And that is a good thing. VW’s innovations show just how efficient you can make a gas powered car, before you even need to think about adding batteries.