It depends on what you want out of that car. Certainly it could be made to run every bit as reliable as a new car. But that requires a certain amount to be spent on the upkeep.

Its all what you want. Any old car is going to give you trouble, to think a W126 of equal age with say 100k miles on it is going to be trouble free is just not realistic.

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2016 Corvette Stingray 2LT
1969 280SE
2023 Ram 1500
2007 Tiara 3200