Audi UK has lent its priceless, 1984, last of the line, unregistered quattro model to the BBC, despite it being so valuable that it is stored at a secret location, in a sealed, dehumidified environment.
The car will appear in spin-off show to Life on Mars, Ashes to Ashes, which features a storyline and props set in the 1980s.
It still has zero miles registered on the odometer.
In actual fact, historically, the model available to customers in 1980 would have had twin headlamp lenses on each side, whereas the final production model has a single binnacle.
"We would never be able to replace this car and its value to the brand is inestimable," said Jeremy Hicks, director of Audi UK.
"Whenever we have exhibited it, we have received a succession of surprisingly high offers, but sadly this particular car, the quattro that started it all for the company in the early eighties, will never be for sale."
The quattro, which Audi insists is spelled with a lower case ‘q’, heralded four-wheel drive for production line vehicles.