Fold-able Car Umbrella to avoid scorching heat

When you get in the car (car parked in the open sun from morning till afternoon), extreme heat related health hazards ruin your health on long term basis. Is there any car umbrella available that could give shade to the car while parked in the day light? A polythene canopy (fold-able) may perhaps give shade to the entire body. Shall that be legally allowed by the traffic department? Can the traffic department look into this as the covered parking is estimated to be available only to 20% of the car owners.