Shoehorning big engines into little roadsters is a classic operation - take the Breckland Beira V8 and Irmscher GT40 for a pair of recent examples - but the tuners at Hartge have accomplished what may be one of the most impressively OEM-looking engine swaps of recent times. The combination of BMW Z4 and M5/M6 5.0L V10 engine is inspirational, and with the car now for sale, it could be yours.

Fitting the big V10 into such a small package as a last-generation BMW Z4 may seem like an impossibility, but the photos illustrate the job was done with a level of expertise that could be mistaken for ease. Though we don't know exactly what modifications had to be made to get the big engine into the bay, it serves as some evidence that BMW's reluctance to stick the V8 from the new M3 into the next-gen Z4 for an M model is more about preserving the hierarchy than about mechanical limitations.

The car is a one-off example built for a customer, but is now available second-hand at a discount price of just €97,900 ($137,800) including VAT, with only 4,860mi (7,824km) on the odometer. The owner lists the car's fuel efficiency rating at 15.8mpg (14.9L/100km) in the combined cycle, 11.8mpg (19.9L/100km) in the city and 17.4mpg (13.5L/100km) on the highway. Those figures aren't exactly attractive with European fuel prices being what they are, but the 328g/km CO2 rating is likely to be just as painful given modern emissions charging.

Some of the other upgrades to the car include custom 20x9in and 20x10in Hartge alloy wheels, a reserved black leather interior and a full complement of luxury features like navigation and heated seats.