When Lacy parks her car at the beginning of the movie, it is a 2+2 model (4 seats) that has a longer wheelbase. The car that blows up later in the movie is a 2 seat model with a shorter wheelbase, showing a different car was used for this part of the movie. The car that blows up has no motor. This is apparent due to the front end of the car sitting noticeably higher than earlier in the movie. Additionally, there is a mark or damage on the driver's door after the explosion that was not on the other car.