Support Vehicles (SV), in other words standard trucks rather than the special that the Stalwart was. That said tanks never took that much support, as in tonnage terms their logistic requirements were not too bad although they are a bit thirsty. Even then though the stolly could not carry very much and was a pig to load and unload. It became obvious that a standard 12000 litre road going Foden with multiple fuel nozzles was a much better bet than a UBRE with a dodgy donkey engine and a single nozzle, even if the panzers had to drive a bit to get to the support.
The other users were Arty, but again once it was realised that the guns might need to fire a few more shells than they thought it became obvious that Stollys were fun but useless. Enter DROPS stage left.
And in the mud Stollys were never great - once that flat belly sat on the mud sticktion took its toll and how we laughed in our Mk1 AECs as we rumbled on past the boat-drivers!!!
On a frozen rough bit of N Germany though stollys were (and probably are with the possible exception of a 6 wheeled Pinz) gravity defying flying machines. And the brakes caught many a German lorry driver by surprise as the stolly in front realised at the last minute dot com that he needed to turn left just here and did the lets stand on the front axle trick.