When the Piaggio MP3 Hybrid goes on sale next year it will become not only the first plug-in hybrid scooter to reach production, but also one of the most fuel-efficient vehicles ever made. It achieves its incredibly frugal consumption—up to 141mpg—thanks to a parallel hybrid system similar to that used by the Toyota Prius. Combining a 125cc four-stroke engine with an electric motor, the leaning three-wheeler is capable of operating on either power source alone or with the two combined for increased performance. But, that's only part of the story; the MP3 Hybrid could be the first plug-in hybrid vehicle—bike or car—to enter mass production anywhere in the world.

With a normal parallel hybrid, the only energy sources are gasoline and kinetic energy harvested by regenerative braking; both are used to recharge the batteries, which then power an electric motor that supplements the gas engine under acceleration and runs the vehicle by itself at low speeds. It's a clever system that can really reduce fuel consumption, especially at low speeds and in stop-start traffic. The only flaw is that the internal combustion engine must burn some fossil fuel to recharge the batteries, meaning the system isn't as efficient as it could be if those batteries were being recharged from an external source. That's where the plug in "plug-in" comes in handy.

Plug the MP3 Hybrid into a standard wall outlet and you can fully charge its battery pack in just three hours. That energy can then be used to make the scooter even more efficient in hybrid mode or enable it to run on its batteries alone, delivering a silent, zero emissions vehicle (it can operate in electric-only mode after recharging its batteries from the engine as well).

In fact, the MP3 Hybrid can operate in any one of four modes: the aforementioned electric-only or three hybrid modes designed to maximize performance, minimize fuel consumption or recharge the batteries quickly. The later could come in handy if you know you're about to enter one of the new emissions-free vehicles only zones now cropping up in some Europeans cities. In maximum performance mode the batteries can boost acceleration by 85%. Considering the 15bhp, 64mph 125cc MP3 is already fairly nippy, that assistance should give it performance equivalent to a 250cc scooter. For the uninitiated, that means a 0-60 time in the 5-second range or enough urgency to easily out accelerate most cars in town.

While several manufacturers have showed plug-in hybrid prototype cars and bikes before (the Peugeot HYmotion3 is of particular note), none have yet entered mass production. If Piaggio can get the MP3 Hybrid into show rooms some time in 2009, it'll be the first manufacturer to bring a plug-in to market and, at 141mpg, it'll easily out-efficiency any of its four-wheeled rivals.

Other than achieving stupendously impressive fuel economy, the MP3 Hybrid looks and works just like the non-hybrid version. The only sacrifice is to underseat storage -- that's where the batteries go -- which still remains large enough to fit one full-face helmet. The two-wheeled front end that gives the MP3 its unique character remains unaltered; that means it'll still lean over up to 40˚, but should be immune to falling over or washing out at speed; advantages that've proven enormously popular with new riders.

The MP3 hybrid will retain a scooter's inherent green credentials too. Scooters (motorcycles too) neither slow other vehicles down -- they don't cause congestion -- nor are they subject to sitting still in traffic, they're capable of safely passing through it. So the MP3 is free to achieve its 141mpg while enjoying shorter journey times than any four-wheeled vehicle.

If you're like us, you're thinking this all sounds really cool, but you'd like to know some numbers. Namely: how far can the MP3 Hybrid travel on electricity only? How fast can it go in that mode? How fast can it go using both power sources? How much will it cost? When will it be available? Unfortunately, Piaggio isn't saying. But, we'll be sure to bring you answers as soon as we have them.

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