What happens when a third electric motor is added to a Tesla Model S? Not additional power, but increased handling prowess. That's according to Roadshow, which recently had a go in a tri-motor Tesla Model S.

But ... surprise ... it isn't actually a Tesla Model S. It's Magna Powertrain's own powertrain design applied to the body of a Model S.

Magna removed Tesla's normal dual-motor setup from a P100D to see what would happen if it placed two motors at the rear—one at each rear wheel—and one up front. The results appear to be superb handling, per the report.

No quantitative data was available to support the claims of added handling pleasure and capability, but they doesn't seem unreasonable. Most electric cars using a similar system, which allows for torque vectoring at the rear, show solid improvements. 

Power of the three 140-kilowatt (188-horsepower) motors totals 564 hp. That's shy of the Model S P100D's power in Ludicrous Mode, but acceleration of the Magna-Tesla was said to be on par with Tesla's electric sedan at other times.

Magna plans to show the system off during the Frankfurt motor show, but as of now, doesn't have any productions plans for the three-motor setup. With more suppliers jumping in on the off-the-shelf electric-powertrain business model, though, perhaps Magna's system has a production future.