....Of clear space to work under their car.
Here's what I do.
I use a trolley jack and some Euro pallets. I cut down the pallets to 450mm x 650mm and some 20mm plywood cut to the same size and pace on top, this gives me 170mm in height each pallet. By jacking front and rear in turn, I go up to 3 pallets high under each wheel which gives me 510mm (20") to the tyres and 610mm (24") of clear space under the car. If you need more room just use more pallets .
Makes a big difference having plenty of room.
And the best part, the pallets cost nothing .