What you haven’t told me is whether your car has an automatic or manual transmission. And that means different things if the transmission has somehow been over-filled.

In the case of a manual gearbox, you’ll find that the extra oil will probably soon be evenly distributed across the bottom of your car as the excess exits the scene through either a breather tube or a seal or gasket.

But if it’s an automatic, the extra fluid could cause the entire transmission to behave strangely, as this type of gearbox relies on the correct internal fluid pressure to select gears, change gears and, in fact, make the car move at all. Again, though, the extra will probably force its way out through a seal or gasket and then you have a much more complicated repair to make.

The best advice is to check the level of the fluid as set out in the owner’s handbook and make sure the level is correct before driving anywhere else.

You are right, it is far too high for that car. Going by Hyundai’s official figures you should be getting between 5.5 and 9.5L/100km depending on the mix of driving you’re doing. I would be making sure all is well with the engine and the electronics that control it, and check the exhaust to make sure it’s not blocked.

We checked with Hyundai and their advice was to follow the service booklet as it is produced with specific recommendations for this market, whereas the owner's manual is a generic publication for many markets around the world. The shorter period is definitely the one to use.