How long did they have to wait before the collision

Two cars are going to crash into each other as part of a destruction derby. Car A is Ford Pinto (liable to explode at a moments notice), while Car B is a Tesla S Series (which famously had non-functional seat belts). The cars will begin 153 meters apart from each other. If the ford has a velocity of 29 and the tesla has a velocity of 31, how long with the audience have to wait in suspense before the catastrophic collision