Featuring two short videos and four photographs of a 6-Series based prototype, the Web site provides no additional information about the prototype other than to suggest that the car in question is “more than a 6-Series” and is “not in its final stage.”

Close inspection reveals the matte black BMW mule has a new front end resembling that of the one-off EfficientDynamics concept revealed at last year’s Frankfurt motor show. Other obvious changes include widened tracks and skinny low-rolling resistance tires on aerodynamically optimized wheels.

Insiders at BMW’s headquarters in Munich have confirmed to Autocar that plans to create a prototype featuring a similar driveline to what is showcased in the EfficientDynamics concept have been progressing for some time. But, they stop short of confirming that the 6-series based prototype featured in the German carmaker’s latest viral marketing initiative is that car.

The video of the new BMW on the Web site reveals it to be at least partly electrically powered, with no obvious engine noise as it accelerates away from a standstill. A single tailpipe at the rear also suggests it houses a conventional engine as part of a gas-electric driveline layout.

The four-wheel-drive EfficientDynamics concept uses two electric motors, one acting on the front axle with 60 kilowatts, the other housed in a six-speed, dual-clutch transmission with 38 kilowatts. The electric motors are powered by energy stored in a battery pack consisting of 98 individual cells charged in part by a 1.5-liter, three-cylinder engine with 120 kilowatts.