A 4 wheeler motorcycle

Sideways on a tilting 4-wheeler: the next generation of fun machines
Enjoy the ride!: http://www.youtube.com/watch?v=j127RX9S7vw&feature=player_embedded

The additional stability and traction you get from a tilting three-wheeler is quite an eye-opener, and they're still exceptionally fun to ride. If you want to take the concept one step further, though, an extra wheel at the back as well can actually make the entire bike narrower while delivering the sort of stability that can let you safely powerslide and drift all four wheels on an oily skidpan.

The extra fourth wheel on the 4MC prototype gives a much broader balance range for the bike's center of gravity - so it's happy to sit at full lean at a standstill OR when being belted around a tight corner.
As the lean angle increases, the wheels move slightly further apart, increasing stability when you really need it - and this works as a backup system when you park the bike and leave it on an angle - the tires grip and prevent the bike from tilting any further.

Steering is handled by a pair of upwardly looping front suspension arms, which allow a nice tight turning circle. Like a bike, you'll countersteer the 4MC into corners - and the combination of leaning into the corners while having the stability and grip of 4 wheels means that the 4MC will use its grip much more effectively than a car can. A sporty tilting 4-wheeler could end up being exceptionally fast in the twisty stuff.
The 4MC is the original work of engineer and company director Nick Shotter. He has specifically designed the 4MC to get its rider through traffic safely yet efficiently.

His interest in safety originated from being injured in a road accident when working as a London motorcycle courier. The 4MC has evolved through Nick's rigorous design process which began in 1989. In 2000 the 4MC won a DTI Smart Award for a Feasibility Study. From 2002 Nick introduced the 4MC to many well known manufacturers with an invitation to buy the 4MC's intellectual property (IP). Between 2004 and 2008 he built a full sized working prototype to further demonstrate the 4MC.

The 4MC’s unique designs are covered by several patent applications. The 4MC’s patent applications, trademark, and prototype are all part of the 4MC’s IP. At this stage the IP is available for sale. Once the patent applications have been granted the IP will be available for either sale or license. The prototype’s purpose is to demonstrate the 4MC. To achieve this it was not necessary to equip the prototype with mudguards, lights, or bodywork. The prototype is very sure footed and terrific fun to ride.

Visit the website: http://www.4-mc.co.uk/
Read full details at: http://www.gizmag.com/sideways-on-a-tilting-4-wheeler-the-next-generation-of-fun-machines/11627/