One car.
Catch is that it will be your last...no replacing for at least 15 years/450K miles.
I am considering replacing my
90 350 sdl (as good as a 90 w/ 170K gets)
94 Legend (...........................117K gets)
78 530i (3.7, 5 spd prstine..etc etc)
03 wrx wagon...making ~280hp quietly
03 SV1000N ...only 5K miles
with an 06 e320cdi
I hear the 07 MB diesels will be V motors. More reliable, more bettah blah blah but I want an L motor.

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82 300D....went to MB heaven
90 350 SDL....excercising con rods