With only 40k on it, the only issues would be related to under use.

Once those are sorted, it would be like starting out with an 8 month old German taxicab, with miles that low on it.

It is probably worth the gamble if it checks out and is not a victim of rust or a refugee from some freeway pileup, if the price is reasonable (and prices are VERY robust for MB diesels like this one.

The W124 is the last of the E class cars with unarguable QC and build quality

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1991 560 SEC AMG, 199k <---- 300 hp 10:1 ECE euro HV ...

1995 E 420, 170k "The Red Plum" (sold)

2015 BMW 535i xdrive awd Stage 1 DINAN, 6k, <----364 hp

1967 Mercury Cougar, 49k

2013 Jaguar XF, 20k <----340 hp Supercharged, All Wheel Drive (sold)