I can't say about the rest of the UK.Here in NI after the usual emissions,under bonnet and interior and lights checks The car is driven by the tester onto rollers,front then rear, to check the brakes and hand brake,a computer graph displays the applied pressure readings and overlays a comparison graph of these on the computer.The tester then moves the car onto plates that are vibrated,up,down and side to side to test the suspension,again a graph shows a comparison between left and right sides(too much variation on any of these readings can mean a fail)Next the car moves onto a ramp and raised into the air,blocks put on the chassis,then the wheel supports are lowered,leaving it suspended so the steering and wheel bearings are checked.The underside then thoroughly checked.These centres are big cold intimidating places,four lanes wide,one for HGV's.Sometimes i can't bear to look at whats happening.