Can anyone help? I'm on holiday in France at present and have just put 1000miles on my newly-purchased W129 SL500, registered March 1998, with 56000 miles on the clock, on the journey down. If I cruise on the autoroute at 130kph or thereabouts it equates to 2500rpm in top and I sense a sort of "trembling" through the throttle as if the car is not happy at those revs. In normal "wafting" around the N roads at low revs the car is impeccable; it consumes no oil and is surprisingly economical for such a big-engined car. But at those speeds and revs it does seem a touch unhappy. Any ideas as to what it might be? I'm using 95RON super unleaded, have used two tanks of Sheel VPower to see if it made a difference to the car and didn't notice anything apart from this "trembling" sensation. Is it something I should be worried about (as in - get to a local Merc garage pronto?)

Thanks

 

Check your fuel filter!