Mercedes-Benz has contacted 900 of its UK customers whose C- and E-Classes could be affected by a problem with the car's fuel injectors.
The problem concerns diesel C- and E-Class models built between last summer and November.
Mercedes says the problem can manifest itself by either the engine running roughly at idle, an engine warning light coming on or, in the most serious cases, the car goes into limp-home mode, where two of the engines four cylinders switch off and therefore the car's power is halved.
While 900 customers have been contacted to have the injectors replaced, Mercedes says it's not an official recall because it's not a safety issue, but a comfort and refinement problem.
'The cars are still safe to drive,' confirmed a Mercedes spokesman.
What happened to a Mercedes owner
'The management light came on and the engine went into limp-home mode - I was in the outside lane of the M60 in morning rush hour,' said one E-Class owner who got in touch with What Car?.
'The car was recovered within 30 minutes, but the dealer says I could have to wait six to eight weeks for the fix.'
Mercedes told What Car? that the fix should take four weeks to fix and customers will be offered suitable replacement cars. Vehicles built after November last year are not affected.