This solar thermal car design is affected by 3 major values: power, weight and cost.
The power can be increased by increasing the size of the solar thermal system or increasing its overall efficiency. The power required to drive the car is also influenced by the overall drag of the car (see Aerodynamic system).
In weight and cost budget we add up the weight and cost of all the nparts. The solar thermal car has a maximum weight and also a maximum cost.