[dmsfrr]

An owner usually wants to believe an engine is original to the car, if that's what he expected, or at least as good as he paid for if it's been knowingly swapped or rebuilt.
But not an undisclosed lesser/older/smaller engine, which can often be the case from dubious sellers.

Depending on the vehicle, and its new owners expectations, a large-ish portion of the perceived value may be tied up in the engine, often with good reason.

The marketing goals for classic and collectible vehicles by auction houses leads to increased prices for the characteristics deemed more desirable on a given vehicle. IE: the promotion of "numbers matching", which filters into the collectable vehicle hobby and resale sites.
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