It seems to be a demo of some stability protection system
The bus and truck without the stabilisers are the ones without this fitted, the ones without will be the demo vehicles.
My five year old car has a stability control system that individually modulates the brakes to keep the car on balance in extreme maneuvers (i.e. the "moose test"). I'd be surprised if people weren't trying to fit it to trucks and buses.
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wheresthefish Partly filled with wrong, Wed 18 Jul 2012, 8:13,
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