Matting a 6-speed auto to the HHR someday...
 

The 2.4 engine is used on the Malibu which uses the FWD 6 speed auto.
What would be the obstacles in the way of matting one of those 6 speed autos to the HHR? Theoretically...

If it would physically fit, you would need to reporgram the computer for the new tranny.

But the fitment will probably be the main issue.

With 2 more speeds I'm betting it is bigger around and longer but don't know for sure.

Speaking of computer, I know in modern cars everything is done w/ the computer. But how many computers does GM have out there? Are they using a few of them with different programs? Do computers have data for different equipment they don't have (how different is a HHR computer from a Malibus, are they the same with different things 'checked' in like a bios screen?)

I just have no idea how advanced or non-advanced these systems are!

Just saw this:

http://www.gminsidenews.com/index.php?page=trans_guide

Anyone else find it strange that the 4T45E can handle more torque than the F35 manual used in the SS, yet the automatic model has been detuned in first and second gear? I wonder if it's a torque steer correction rather than driveline protection.

The 4T45E also handles more power than the new 6T40.

Not very likely. The 6 speed auto is only offered on the Malibu with the 3.6L V6 SFI engine.

For now, that's the 6T70 on the 3.6. The new 6T40 is replacing the 4T45E on the 4-cylinder models when they shut down Windsor transmission. It appears from that website that the case isn't a whole lot different from the 4T45E to the 6T40, so it could probably be adapted, but the 4-speed will handle more power.

Ahh the play of words can be so misleading....

Hydra-Matic 4T40-E/4T45-E Transaxle (MN4/MN5)
Maximum engine torque: 190 lb-ft (260 Nm) (MN4)
205 lb-ft (278 Nm) (MN5)
Maximum gearbox torque: 325 lb-ft (440 Nm) (MN4)
325 lb-ft (440 Nm) (MN5)

There is a differance between gearbox torque and engine torque. That is why they have to detune the SS. The F35 is rated for 260 lb-ft in gearbox and engine torque.

i think you will see a 6 speed auto fairly soon. Only reason i say that is because all the automakers are scrambling to make more fuel effecient vehicles and if a 6 speed auto gets a car/truck/van 2-3 more mpg, they gonna find a way to do it. Another thing that may happen is the return of the cheap and basic car....less luxury ..less weight....small effecient gas misers. Time to re-invent the wheel!

I'm not sure a six sped will help that much. Economy driving in 6th gar wont be pulling much less rpms for better economy. Just more shifting for the auto. Now my four speed auto is running around 2400 rpms at 70. On any hills the car downshifts. The torque just isn't in that engine at low rpms to a support lower final gear for better economy.