General Motors Saturn MP2 / MP6

Saturn's own transaxles — the MP2 and MP3 manuals and the MP6 and MP7 automatics — in the S-series.

⚑ Saturn designed and built its own, which is the single most useful fact: these share nothing with any other General Motors gearbox. A parts search across GM's catalogue returns nothing applicable, and the 4T40-E and Getrag F23 that other small GM cars used are unrelated.

The MP6 and MP7 automatics have a poor reputation and it is largely earned — but the commonest reported failure is the differential rather than the gearset, and it is frequently misdiagnosed as a rebuild when the noise is a bearing.

The manuals are the better half and are what most surviving S-series carry, since the cars outlived their automatics.

Saturn closed in 2010 and the parts network went with it, which is the real constraint on repairing one now rather than any difficulty in the work.