I went through the same thoughts of TDI or 300TD, 2 and a half years ago.

The 300TD is an incredible people/stuff hauler and amazing road trip machine. It is very fast and comfortable. Mine gets about 22MPG on b99 in town and about 28 highway. This is much less mpg than a TDI, but it holds 7 people or a family of four and a ton of gear. That said, I think $1,000 for maintenance is not a bad trade for no car payment. I did the tranny at 277k miles and that was $2k, so over my two and a half years, I think I am at ~$1,600 per year. That feels pretty damn cheap to me.

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87 300TD -"Frita"