(About 25% of cars are sold with thinner ‘space-saver’ wheels, which allow you to travel at a limited speed for a short distance, to get yourself to a garage. Others have ‘run-flats’, reinforced tyres that allow you to continue on with a puncture for a limited time.
Almost half of new cars are sold without any spare wheel at all, they are simply equipped with a repair kit: basically some sealant and an air pump that you use to temporarily fix the tyre.
Q. Why are they doing this?
A. Money.
Not providing a spare wheel can easily save manufacturers around £100 per car.