Solve this and a byline awaits

Here’s a mystery for any budding investigative journalist.

I took my car to a bodyshop after a minor prang. A chap with a clipboard went over very inch of it, noting the tiniest dent or blemish lest I accuse them of not looking after it. He did the same with the courtesy car and then carefully noted the amount of petrol left in each tank. Mine was half full. I agreed and signed his form.

A week later, I picked it up all valeted and shiny and headed out of the industrial estate. But before the first 100 yards, the fuel light came on. I was running on vapour.

I checked the form I’d signed. Half-full when it came in. 19,001 miles on the clock. Now it was empty, but still 19,001 miles on the clock.

I reversed up, asked two people from the office to come and look and posed the questions:

Did someone use it and turn back the clock?

Did someone deliberately add on 100 or so miles to the figure before handing it to me to sign? I never checked the mileage.

Did someone siphon the petrol out?

I got red faces and a cheque for half a tank. But, as yet, no answer. May be worth a few pars in the local paper when I do.