Same question asked on the forum 14 years ago
For pre-2009 cars, the Motor Vehicle tax (Kraftfahrzeugsteuer) is calculated based on engine size, split into blocks of 100cc. Most 1.8s are a bit less than 1.8, so the owner pays something like 18x100x whatever the applicable tariff is. The BP engine is 1840cc. You don’t to pay a 40cc rate. Round up to 1.9 lets the consumer know when they are buying the Mk1/2 MX5, they are paying the tax for a 1900cc car.
Which seems a good explanation, and the calculations are true; a 1840cc pre 2009 petrol car, non Euro 1, is the same to tax as a 1900cc car, but more than a 1798cc car. Feel sorry for owners of 1.9 205 Gtis, that extra 5cc costs them 25 Euros.
But
