As studied earlier, weight is the kind of force that the earth exerts on us. As shown in the Fig.2.1 there are multiple forces applied on a car from different direction. Gravitational force puts downward force on the car, engine puts forward force etc. some forces gets balanced by equal and opposite force e.g. downward gravitational force gets balanced by equal and apposite force exerted from ground.
Car moves forward when forward engine force overcomes frictional force from the road.