Compared to an SD, a 400E will feel incredibly fast. I have owned one since 1993. The 500E is a faster car due to a larger engine and shorter gearing. The thing that hampers a 400E is its tall first gear. Mine will hit 50 in first gear meaning that it takes quit a lot of time to hit 30. Beyond that, it is pretty quick.

Original specs indicated a 7 second 0-60 and a 15 second quarter mile. As I said, much time is lost getting to 30 from zero. Above 30, the car is as fast as my old Ferrari which only does a 14.6 quarter mile and hits 60 in 6 seconds.

Probably the best upgrade for a 400E is would be a 5 speed automatic tranny. That would lop off a nearly a second in the 0-60 time. I would leave the engine alone as it is a very good engine.

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Lawrence Coppari

2002 SLK32 AMG
2005 Acura TL
1987 328GTS
1986 944T