Buyer beware…

ENGINE

Check the supercharger’s separate cooler isn’t leaking. There’s a lot of plumbing around the engine so ensure everything is fluid-tight and rust-free.

SERVICING

Variable but usually every 12k miles. Brake fluid every two years, coolant every four, transmission oil/filter five.

ELECTRICS

The SL55 is an auto electrician’s nightmare. Known weak spots are the traction control system, by-wire throttle, electric windows and tyre pressure monitoring system.

SUSPENSION

Check the ABC system for rusty pipes and leaky seals, which cause the hydraulic pump to run dry. It can fail at 60k miles, too, if fluid isn’t changed. A new one is around £1500. In 2008, the system was recalled for possible acceleration sensor failure. Suspension struts are a common MOT test fail.

BRAKES

The Sensotronic Brake Control (SBC) was the subject of various recalls so check the car was seen. The system is designed for around 100,000 miles before car goes into limp mode.

BODY

Dents in aluminium body panels can be a devil to put right. Check the boot for damp, which can short the roof motor and the central locking vacuum pump. When roof is raised, listen for creaks that could indicate poor alignment. Look for rust on the rear wheel arches.