[Flyinghippo]

Think of those little toy cars you pull back on until they make the noisy clicks when the inside spring is fully wound,,, then you let it go across the room.
Take that concept and modify it. What I would love to "try" is something like that on one of my Rangers to capture braking energy and reuse it to take off from stop signs or stop lights. I'm sure the amount of energy captured would be maybe 2/3 of the power needed to get back up to speed of maybe 30 mph.
The mechanism would be a chain driven off of the rear of the transmission and hooked up with a brake and clutch to a series of multiple garage door coil springs, or maybe some other spring. Have the springs connected one to the next, to the next, to the next, to the next etc via chains. I don't know if it would take 10, 20 or more springs to capture and hold the energy. At the other end of this mechanism is a brake and clutch to hold the sprung chains energy. That energy is ran foreward with a shaft up to the rear of the transmission which is of course hooked up to the driveshaft.
When its time to takeoff from the stoplight/stop sign the clutch at the far end engages and the far end brake is released and away you go taking off and hopefully not spinning the tires. I'm sure someone thought of this 100 years ago. The down side is I'm guessing this series of chains, clutches, brakes, springs, frame, guards, controls etc would weigh 500 pounds or more and cost me $1000, $2000 or more to build and take up half or more of the bed of my Ranger.
So I'm guessing the motor/generator setup in a Prius works a lot better than my idea described above.