Porsche resale values are so strong that a Boxster bought new in 2001 for £33,333 and sold this month for the going rate of £31,395 will have lost just £2,038 in value, or £13.06 a week.
This astonishing fact is just one of the revelations in our all-new Parker's 100 survey. It works by tracking the prices of Britain's most popular 100 cars every month.
We've split them into sales sectors (small cars, family cars, 4x4s, luxury) and measure depreciation against their new price. The aim is to clear up confusion for owners struggling to understand the part-exchange price a dealer offers for their car.
Among the best performers are the Mercedes M-class, BMW X5 and the new Mini, all retain more than 80% of their new value – showing that the right badge always counts. Audi's TT and the Toyota RAV 4 are also strong performers; in general it's the sports cars, 4x4s and hot hatches that hold their value best.
As expected, the heaviest depreciators are family and luxury cars, especially the last versions of older models that have been replaced. The old shape (2000-2002) Nissan Primera props up the table, holding just 41.2% of its value over three years and with mileages of about 10,000 a year; old model Vauxhall Vectra and Toyota Avensis are both near the bottom of the Parker's 100.
Of the current models, Citroen's C5 is the heaviest depreciator. It loses 58% over three years or £54 a week thanks to widespread discounting and generous, long-running cashback offers when new.
These mainstream cars suffer the classic problem of being bought in huge numbers by the business fleet buyers and hire companies sold on relatively quickly, hitting values hard. But for the private buyers on the forecourt, it makes them a great used buy, because they get a lot of car for far less than list price.
Luxury cars tell a similar story. A pampered 2001, Y-reg BMW 735 or Audi A8 with full service history can be bought for around half of their original prices. Both have recently been replaced with new models, but are still superb cars. But unlike family cars, which will hold their value better in the next few years, the big luxury models' sell-on values will continue to plummet.