Either Volvo is going back in time or there's a new form of propulsion on the horizon for the XC60, because the Swedish brand just trademarked the names XC60 B4 AWD and XC60 B5 AWD nameplates.

Given Volvo's naming structure, we know that B4 and B5 will refer to the XC60's powertrain.

Currently, Volvo sells Diesel engine under the D4, D5, D6 (etc.) badges, while gas powered cars start with T: T5, T6, or the plug-in hybrid T8.

Go back in time, though, and Volvo used to designate its engines with B names: 1944's B4B engine, for instance, found its way into the PV and the Duett; while the B18 graced the engine bays of every US Volvo from 1961 to 1974 (with the exception of the 164).

The name came from Bensin, the Swedish for gas, with the numbers generally referring displacement. In 2010, though, that all stopped when Volvo switched the B for a T.

And since Volvo is making such a big deal out of its electric push, we'd guess that the new B motors won't be burning anything at all. A quick stop by Sesame Street will tell you that B is also for Battery, which we would hazard to say suggests that Volvo is planning on releasing an all electric XC60.

If rumors of range from its sister brand, Polestar, are to be believed, an electric XC60 could have a range of up to 350 miles, putting it well ahead of most electric vehicles on the road today.