Em primeiro lugar, depende do orçamento, então o processo é decidido de acordo com ele.
Como nos países desenvolvidos, como os Estados Unidos, a obtenção de sucata de ferro-velho e a explosão não custam muito, mas em pequenos filmes de orçamento eles substituem o caro carro por um carro barato e depois o estraga. Como no exemplo a seguir da Corrida 2
Onde você pode facilmente identificar que dois carros diferentes são usados, um para show-off e outro para o propósito da explosão.
Da mesma forma, carros de brinquedo também são usados em filmes pequenos que parecem carros reais, mas não são. Da mesma forma, os carros de brinquedo são misturados ao carro real com CGI e se tornam uma boa opção.
Mais um exemplo do cracked.com está aqui -
In The Dark Knight -- The Big Chase Scene
Two specific points during the insane car chase at the halfway point of The Dark Knight are so over-the-top they seem like they would have had to be computer-generated, if for no other reason than they would have killed the stunt drivers.
The first is when the Batmobile first shows up to take out the Joker's convoy. It speeds in ...
... and offers what equates to a vehicular uppercut to a garbage truck.
The scene ended up in the trailer and inadvertently encouraged a bloat of fanboys to flock to their keyboards and pound out protests against the fake-looking CGI in the movie. But as Christopher Nolan has proved time and again, he doesn't mess with that shit if he doesn't have to.
No, what you are actually seeing there is a complete one-third-scale model of the Batmobile, the garbage truck and a large section of lower Wacker Drive in Chicago.
They stuck the two vehicles on a guide and smashed those mothers together. What you see in the film is the result.
Even the damn 180-degree move that the Batmobile pulls off at the end was done by a radio-controlled model.
So what about the climactic moment in that scene when they flip the Joker's 18-wheeler after Batman clotheslines it with a grappling hook? If that was a model, it was pretty goddamned convincing.
The flipping of the semi was accomplished with a technique known in Hollywood as flipping a real goddamned semi. To get the mind-boggling amount of upward force needed to lift the big bastard head over heels, the FX crew built a huge steam-piston mechanism in the trailer.
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