Money spent is not value added
A modified BMW is priced by what a buyer wants, not by what the previous owner spent. Parts chosen for one owner's taste narrow the audience rather than widening it, even when the parts themselves are expensive and well regarded.
Reversibility is the practical test
The most useful question is whether the car can be returned to factory specification, and whether the original parts come with it. A car with the stock components boxed in the garage is a materially different proposition to one where they were discarded.
- Retained original parts reduce the effect of most cosmetic and exhaust changes.
- Engine tuning raises questions about warranty status and long-term stress.
- Irreversible changes such as cut panels or removed interior trim narrow the buyer pool most.
- Professional installation with invoices is treated differently to undocumented work.
Disclosure beats discovery
Modifications found during an inspection cost more in negotiation than modifications disclosed in the listing. Our guidance throughout the platform is to state them plainly and provide the documentation.