Algodoo

Looks good, but you can make it way simpler by changing a circle's radius. Then the whole gearbox will have less weight and you can use the gear variable divided by something as I do.
My gearboxes are scripted like this:

radius = {Scene.my.G < 0? {x}:{y + scene.my.G / z}}

Scene.my.G should go from -1 to 6.
And for the neutral, just add a script in the output hinge like this:

autoBrake = {Scene.my.G == 0? false:true}

That's way simpler than having 16 variables that take lots of memory and lags if you have a slow memory (I have 333 MHz).
Also that would make everything easier, because you've got 6 hinges constantly asking for what should be it's torque.
This gearbox seems good, and I don't have any lag in this scene, but your Subaru is unplayable for me

Thanks for the tips man! Sorry to hear that my Subaru is unplayable for you

The good news is I'm working on a lite version that's more simple and faster
And I'll probably use the gearbox you described for it.

Don't worry, I've bought an AMD X6 today!
I'll throw my pentium4 to the cellar

P.S Take a quick peek in my Golf MK4 or my Fiat Bravo's gearbox if you want an example

Did you buy a new motherboard and stuff for it?

for a pentium 4? It's not worth it. My computer is from 2002, it had an amd xp+ at 1.66 GHz, 128 mb of RAM, a 64mb nvidia and an agp8x motherboard. Now i've put it the best videocard that the motherboard can support (256 mb), overclocked the video card, and it has 2gb ram now and an overclocked AMD from 2.1 to 2.32GHz (the maximum frequency of the motherboard) equivalent to 3GHz pentium4. In other words, crap

My new comp has an X6 @3.5GHz on turbo (it's unlocked, so I'll buy a water cooler and oc it), an integrated radeon that i'll replace with a decent videocard, and 4gb. I'll put it 4 more later

I meant did you get a new motherboard and everything to support your new CPU xD
(which is a stupid question because you would literally have to)

Nope, I've just bought one from zero

If it's scripted, why not just change "gear" radius?

Because I like things to be somewhat mechanical. Just changing the radius is boring.

Kilinich, that's what I proposed xD

How do you get the stretchy hinge

ive been trying to know.