The oil on my car was running low so I topped it up and then did a short journey and the oil was gone by the time I got home. There hasn't been any leakage on the road so I have no idea where the oil could have gone or what could be wrong with the car.
You may have what is called oil consumption. The engine may have for some reason started to consume oil into the engine while it is running. This can be due to a clogged crankcase ventilation system, broken or seized oil control rings on the pistons, or intake valve seals are leaking.
Any of these problems will cause the engine to consume oil. There is always some oil that is consumed by an engine and most manufacturers will test the amount used doing a oil consumption test. This test starts with inspecting for any oil leaks on the engine first. Then a fresh oil and filter change is done. Dive the vehicle for 1,000 miles and return to have the oil topped offed to see how much oil is being used. If your car used more than one quart of oil over 1,000 miles then it may be considered excess oil usage and will need further diagnosis to isolate reason your oil fluid is not operating as it should.