The idea is to enhance its grip on the road and ensure good visibility. According to the Spanish Traffic Department, a million and a half cars with tyres in poor condition are using Spanish roads. A well-shod car will have its tyres at the right pressure and the tread in good condition (better above the legal limit).
Defective shock-absorbers lengthen the braking distance and can cause aquaplaning.
Good visibility implies a window washer tank full of soapy water and wiper blades in good condition.