So... Extended test drive in a C43 coupe today with my factory order due to be delivered early March. I had already expressed concern to dealer RE crabbing issue, got usual winter tyres line from a senior technician but dealer agreed to let me take the car out on my own to form my own opinion.
Car was a 66 plate, 1400 miles, 19" Dunlop summer tyres as standard fit at the factory. Dry roads with 2-4 degC showing on car thermometer.
1st thing I did was full lock slow speed turns in the dealership car park, crabbing issue was evident but seemed more like mild steady tyre slipping rather than the sudden knocking/jumping that has been demonstrated on the GLC videos on youTube. It did it mainly forwards but also slightly in reverse. 20 miles of mixed driving later tried again with the full lock turns on tarmac and block paving with no tyre slipping/crabbing/knocking at all. Car left for 30 mins and the issue returned but again was much more minor than on the GLC videos (air temp still 2-3 degrees) 15 miles of driving later back to the dealership and there was still a little bit of the crabbing but not constantly.
So my thoughts about the car and my order... I have experienced the issue first hand, whatever the underlying cause (tyres or drivetrain) the tyres do slip slightly on slow speed and full lock. It was only a slight comfort issue for me, I do not feel it would be a safety issue in terms of the car suddenly jumping sideways resulting in a crash with another vehicle/object whilst parking. If it does increase tyre wear then I can live with this as long as it doesn't eat through front tyres in 7000 miles. I only intend to keep the car for around 3 years so any drivetrain faults/failures would be under warranty during my ownership. The rest of the car was great, lovely interior, engine and gearbox; everything I remembered from my first drive and the sports exhaust sound still made me giggle on up and down shifts.
Is it a concern? Slightly, tyres will still wear, car will be covered by manufacturer warranty, if MB admit there is an issue and produce a fix then the car would be recalled for the fix. Residuals are an unknown so am looking at PCP again should I want to walk away after 3 years. There have been a couple of C43 owners who are aware of the issue only after collection and have expressed that they would still have bought the car if they were aware of the issue prior to collection.
Car is still on order and am still eagerly awaiting collection in March.
These are my opinions from my drive today, I wanted to share them with everyone else to try and help others in a similar position make an informed decision but the best advice is still to take another test drive and experience it for yourself, I could fully understand if others decided not to proceed with a purchase.