Toyota's RAV4 EV features an electric drivetrain and battery systems that were designed and built by Tesla Motors. Photo credit: Toyota.

It seems like a formula for electric-car success: Take one of your most popular gas-powered models, and have the whizzes at Tesla Motors (TSLA -3.55%) convert it to all-electric power using their own special high-tech sauce.

It may seem like a great idea, but the reality hasn't worked out so well for Toyota (TM -0.91%) and the Tesla-powered electric version of its RAV4 SUV. Last week, Toyota announced big incentives on the battery-operated RAV4, and in this video, Fool.com contributor John Rosevear looks at why this winning formula isn't working out so well in practice.