There was that one, but it is another name: http://www.imcdb.org/vehicle.php?id=74289

i could have sworn we had one.

But there is none with that name currently on the site

Cadillac Fleetwood Brougham D'Elegance (35)

Right. Then the Leyland wins, though that with its two "Mk" it is cheating too
After some stretched limousines, we have :
Land-Rover 88'' Series III County Station Wagon (36)
Vickers-Armstrong Infantry Tank Mk.III Valentine Mk.I (35)
some cars with long name due to the body type rather than the real model (e.g. Citroën 10 Conduite Intérieure Commerciale or Triumph Vitesse 1600/Sports 6 Convertible)
further we find a Harley Davidson Ultra Classic Electra Glide 1450 (32)

you can't count stretched Limousine as part of the name! (I don't believe i've ever seen it written on a vehicle?)
In that case you could add 'sports coupe convertible' to the end of many cars, adding 22 characters.!

That chinese name looks more like a serial number than a real model name.
Currently the longest names on the site are:
Lincoln Continental Town Car Stretched Limousine
Leyland A27M Cruiser Tank Mk.VIII Cromwell Mk.IV
Cadillac Fleetwood Brougham Stretched Limousine

Cadillac Fleetwood Brougham - 25 characters

http://www.faw.com/product/product.jsp?FileName=zk_zhc_ow&left=zk_zhc
The Chinese built FAW CA5313CLXYP7K2L11T4!!!
(22 Characters if you count the manufacturer name!!)