5AT in Mazda5

[07MZ5SA]

That the 5 speed has fewer wear (and other) parts than the 4 speed is a fantasy.

I've read (can't find the source now) that when Toyota switched from 4-speed to 5-speed automatic (FWD) by adding an 2nd+OD (or 3rd) gear. Of course, gear ratios were rearranged for even spacing.

In this case, number of parts are the same between 4 and 5-speed models except electronics.

 

[rodslinger]

Dodge did the same thing on their (5)45RFE transmissions in the Jeeps, Daktoas and Rams. It actually has six forward gears but their TCM programming only utilizes four or five upshifts depending on year and uses an alternate 2nd gear ratio on downshifts when passing. It's basically 1st, 2nd, 2nd prime, 3rd, 4th (overdrive) and 5th (double overdrive if enabled) It skips 2nd prime on upshifts. Downshifts under load will go to either 2nd prime or 3rd depending on speed.

I think I read they are doing the same thing in the new six speed autos in their new FWD cars also. Actually has seven forward ratios but setup something like 1,2,3,3p,4,5,6 and only uses the 3 prime on downshifts.