I believe the '96 is the most reliable of them. It has the old-style, vacuum-operated transmission (no software bugs to deal with and easier to service), no turbo to warp the air filter box or leak oil, and no MAF that goes bad, though you may get to deal with sticking intake flaps instead. Of course the non-turbo OM606 is quite weak compared to the turbo version, but it's more than adequate around town and normal highway driving.

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL