need to know for a paper on automotive engineering.

no theres not ,the most shift manual is only 6

To the best of my knowlege no

found some cool stuff but no 12 speed gear boxes

http://cars.blogs.ca/2006/07/25/porsche-designs-7-speed-dsg-gear-box/
http://porschetractors.com/

never knew that he made diesels much less tractors

Yes OF Course.. Porsche took gearboxes from scania and MANs and installed them in 928 Turbo. Its got space for one person and the rest of the space is taken by the gearbox.

No. The manual transmission with the most gears is the 6-Speed. Some cars have 7 and 8 speed automatics. No manual though.

No - at present no one in the auto industry is making a 12 speed gear box. there r a few CVTs that could probably be programmed with 12 preset ratios, but that would not really be a true 12 speed. And it is also hard to imagine what kind of engine would benefit from 12 seperate gears over the speed ranges available to a car.

The current top of the line gear box from Porsche would be the 6 Speed Sequential Manual that is used in the RS Spyder, though there is no street version of this currently used (this may have been developed from the version Porsche originally looked at for the Carrera GT, but found lacking in street use application). Porsche has recently put in patents for a sequential shift 7 speed that may be seen as early as next year, & almost certainly by MY 2009.

Nope

Be sure to vote for your best answer!

No.
BUT! If you put in a Gear Vendors overdrive unit, the 6 speed would pretty much be a 12 speed.