Earlier this month information from leaked UAW documents revealed the Corvette may get a new dual-clutch transmission and now reports are claiming GM is also working on new seven and eight-speed gearboxes. The key now for GM is determining whether the improvements in fuel economy and performance would justify the cost of engineering them into a vehicle.

The executive director of GM Powertrain’s Transmission Engineering, Jim Lanzon, told The Car Connection that every possibility is being looked at including a similar gearbox design to the one used on the high-performance BMW M5. GM has the technology but as Lanzon explained, “there is more to making a seven or eight-speed transmission than adding more modules. You’ve got to be concerned about the parasitic losses that neutralize the fuel-economy gains.”

New computer design tools have sped up the development of GM’s recent gearbox technology. Where once it would take close to a decade to develop three or four new transmissions, with the aid of computerized tools GM has launched nine new six-speed transmission models in just four years.

Dual-clutch technology is slowly filtering to other companies after the Volkswagen Group first pioneered the gearboxes in their mass market vehicles. Mitsubishi’s Evolution X and the Nissan GT-R both get dual-clutch gearboxes and Ford is bringing it to market very soon.
[url]http://www.motorauthority.com/cars/general-motors/gm-considers-eight-speed-gearbox/[/url]

There are Lexus with 8 speed autos, yes?. Their big LS 470 (4.7L V8) gets 22mpg on the highway, and it's a big sumbitch. Not sure if that is a major improvement over what it might have with a 6 speed...

I am not so sure all these gears are a better idea.

6spds seem to me to be enough... modern engines have such flat torque curves, that more than that seems like bragging rights more than a real tech advance.

I know MB has a 7spd... and the big Lexus getting 22hwy isn't all that spectacular, cause I doubt top gear is any different than top gear would be on a 6spd... the end result? more options in between... BFD.

I am not saying that 4spds are the way to go, no, I just feel that the 6spd is the optimal compromise.

I think youre missing the big part of it all here Bogus, when it comes to vehicular economy, having a car labouring in too high a gear is every bit as negative on fuel economy as having one screem its arse off for no reason under very little load.

You dont simply get the best economy from selecting a higher gear too soon and labouring, this will result in lower RPM yes, but the engine will use MORE FUEL then it would if it was under less load at a slightly higher rpm.

Keeping RPM down low is only a very small part of fuel efficiency. Mercedes Benz know this VERY well, and their cars are always geared exceptionally well.

The more gears you have to choose from, the better chance you have of keeping in the sweet spot for the desired mode of operation. Flat torque curves or not, there will always be a point of best efficiency with every engine.