Selling a car that will not run.

"It will not start" is worth less than a diagnosis

A buyer pricing an unknown fault has to assume the worst plausible cause. A buyer pricing a known fault prices the actual job.

If the difference between those two is an engine, the gap in the offer is enormous. A diagnostic reading, or even a clear account of how it failed, is one of the highest-return hours a seller can spend.

What determines the number

• Whether the fault is known and evidenced
• Whether the car turns over, moves under its own power, or neither
• Parts value on that model — some are worth far more broken than others
• Whether it can be pushed and winched, or needs specialist recovery
• Body and interior condition, which still matters for parts
• Whether the V5C is present

Repair, sell or scrap?

Broadly: repair if the fault is cheap relative to the car's value; sell to a specialist if it is expensive but the car is otherwise good; scrap only when neither the parts nor the shell are worth more than the weight.

Salvage buyers and scrap buyers are different markets with different numbers, and plenty of cars that owners assume are scrap are worth considerably more to someone breaking them for parts.