Walk any auction listing and you will find the same phrase in a thousand descriptions: well maintained. It is the least useful sentence in the hobby. Every seller believes it. Almost none of them can prove it.
The gap between believing a car was well maintained and proving it is where the money sits. A buyer looking at two otherwise identical cars is not comparing condition, because condition is visible and both cars look fine in photographs. They are pricing risk. The car with a folder is the car whose deferred maintenance is known. The car without one is a bet.
Which records carry weight, roughly in order: anything involving the engine or gearbox internals, timing service on an interference engine, suspension and brake refreshes with dates and mileages, and any work done by a marque specialist rather than a general shop. A receipt with a shop name a buyer recognizes is worth more than the same work documented by an unknown garage.
What carries less weight than owners expect: oil changes on their own. They matter enormously to the car and very little to the buyer, because they are cheap, frequent, and easy to claim. Their real value is cumulative. Eleven consecutive oil changes at consistent intervals tell a story about the owner that no single receipt does.
The practical failure is not that people neglect their cars. It is that they do the work and lose the paper. A folder in the glovebox survives until the folder does not. An email search for a shop's name works until you change email providers. The record has to outlive the filing system, and it has to be handed over in one piece at sale time.
That is the entire argument for keeping a real log. Not because it is satisfying, though it is. Because at the moment of sale, the folder is the difference between a number the buyer accepts and a number the buyer negotiates.
Keep your own records where they can’t go missing.
MotorStable holds the service history, the registration, and the documents, and hands them back as one report when you sell.