It lays a very basic and general foundation. It helps in keeping learning fun and gives an easy and stress-free way of relating to numbers quite subtly. Most kids like a sense of accomplishment and progression.
The car stacking activity presents this first and foremost. With the small knobs that your child will have to handle, already their neural pathways are being prepared deeper abstractions. This sense of building, stacking up, progression and the correlative colored numbers to the toy cars, all conspire to give your child an unforgettable lesson in math!