The Situation
Marcus runs a compact pitch of around thirty cars. He priced each one the way most independent traders do: purchase price, a glance at what similar cars were advertised at, and a number that felt about right. The problem was that the real cost of a car only arrived later — a set of tyres this week, an MOT and a cambelt the next, a diagnostic and a valet after that.
By the time a car had been through prep, the figure that actually mattered — true cost against sale price — had never been added up in one place. Purchase price lived in one folder, prep receipts in another, and the margin was whatever Marcus remembered it being.
The Trigger
One car settled it. A tidy hatchback he had sold on what he had written down as a £600 margin came back to bite him — the clutch and cambelt he had paid for before the sale had quietly eaten the lot. It was not a £600 car. It was barely break-even, and he only found out by accident.
What Changed — True Margin on Every Unit
Every vehicle now records its purchase price, each prep cost as it is spent, and the asking price in one record, so the margin per unit is live and already includes recon. The stock list sorts by real margin, and no car gets priced without its prep spend sitting on screen. Marcus moved the whole pitch onto car stock management software and priced the next arrival with the true cost in front of him for the first time.
True Margin Per Car — Before and After
Average true margin per car sold
The number did not climb because Marcus started charging more — it climbed because he stopped accidentally underpricing cars that had swallowed hundreds of pounds in prep before they ever reached the forecourt.
Where the margin was leaking
Cars sold below £250 true margin — before vs after
Before and After
| Metric | Before | After | Change |
|---|---|---|---|
| Avg true margin per car | ~£190 | ~£500 | +163% |
| Cars sold below true cost | ~1 in 8 | none | |
| Prep cost recorded per unit | no | yes | |
| Time to price a new arrival | guesswork | same day, costs visible | |
| Extra margin banked / year | — | ~£14k |
Key Takeaways
- Margin you cannot see is margin you give away. Prep spend that lands after pricing quietly turns profitable cars into break-even ones.
- True cost belongs with the car, not in a shoebox. Purchase price and recon in one record is the difference between a real margin and a guess.
- Sorting by margin changes what you buy. Once Marcus could see which cars actually paid, he bought more of them.
- Small pitch, same discipline. Thirty cars is more than enough for hidden prep to cost real money over a year.
