Rupert Beer, 51, from the east Bavarian town of Windischeschenbach, came down to his garage to find the door forced open and his car in a state of disarray.
Not only was the number plate hanging off his prized red Citroën Picasso, but all along the bonnet Beer discovered deep scratches and dents, wrote the Bild daily on Monday.
"The windscreen was so smeared, that you couldn't see through it," Beer told the paper.
Puzzled at first, Beer bent down to get a closer look and found evidence of a lovers' tryst - a jacket, a mobile phone, a used condom and a hair pin. Armed with these clues, it wasn't long before Beer had tracked down and identified the bold pair, both living nearby.
The couple did not deny breaking in, or having sex in Beer's garage, but they said they had had nothing to do with the damage to the car, which Beer said would cost him €3,000 to fix.
"As far as I'm concerned they can do what they want but then they'll have to take responsibility for it," said Beer, who plays the tuba in his local fire-brigade band.
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The couple are due to appear in court on October 16. Measurements are being taken of the lovers' height and weight to evaluate whether they really could have damaged the car by having sex on it.