Do you have formal confirmation from anyone that this is road legal in the UK? As a layman I understood there to be two parts to type approval in respect of towing. First that the vehicle must be submitted for approval by the manufacturer. Due to the cost of this process quite a few vehicles that are not commonly expected to tow are not certificated for towing.
E.g.
Witter towbars UK FAQ
And second that towing brackets themselves must also be submitted for type approval.
Regardless of legality I assume that fitting a towbar would void any M-B warranty (since they don't approve the vehicle for towing)?
Good questions:
The first point is that anyone can, in theory, apply for Type Approval for a vehicle. As you say, it is usually done by the manufacturer, but anyone with enough time and resources can seek that approval – though they’ll need a design data set (drawings, build standard etc) to support the application – then there’s the rigmarole of all the safety testing etc.
Part of the approval process for a vehicle intended for towing would consider that as well, and would specify the attachment points for the coupling.
Then, as you correctly say, the bracket itself has to be approved, which from what I understand is to show that it meets the interface as defined in the original (vehicle) data set.
What it seems that the German companies are doing is exploiting the fact that the C219 CLS shares all its floor plan pressings with the W211 E Class – hence all the attachment points are already present – and presumably are referred to in the data set for the W211.
They then present to the Kraftfahrt Bundesamt a set of design data which is based upon that for the W211, but with deltas where appropriate for the C219, and presents a reasoned argument as to why it is legitimate to read across the clearance.
The Kraftfahrt Bundesamt has assessed that body of evidence and concluded that the C219 is capable of safely towing hence they have issued an updated Type Approval Certificate which addresses all those numbers that you have quoted from Witter, including a Gross Train Weight of 2370kg + 2000kg (towed) though I suspect that in practice this might be constrained by rear axle load.
Now technically under EU Regulations there is a Mutual Recognition Scheme which ensures that a Type Approval given by one state’s regulatory body is recognised by all other states. On paper that means that VOSA are obliged to accept it, but as someone who has been involved in fast jet airworthiness I wanted to be squeaky clean:
Therefore I contacted VOSA prior to importing and fitting the bar, sent them the revised Type Approval Cert and received written confirmation that my interpretation is correct and that I may legally use the bar in UK.
I also have what is in my terms a Letter Of No Technical Objection (LONTO) from M-B UK, and have informed my motor insurance provider.
The LONTO makes mention of voiding any warranty, but if a W211 can do it then I can’t see why the C219 shouldn’t be capable. There is mention of a cooling modification (an F G Fan) but I’m told that it will only apply if operating hot and high near the max load limit, and my race car/trailer combination only weighs about 1100kg.
As you might imagine this took a fair bit of research of part numbers etc and other work to get all the ducks in a row....
