Although model kits are not used in movies as much as they used to be, thanks to things like CGI they are still used in things like explosions as they cost a lot less than using CGI technology. It would certainly seem that movies have relied on models for a very long period of time and truth be told they still do today.
If the film is not actually going to be using models for the explosions they may still do a few tests using models instead of wasting money. On ocassions they film something like this and if it is good they keep the scenes with the models as they are cheaper. The fact is that models can look surprisingly realistic nowadays because the technology for making them has improved so much. More often than not you will see RC tanks in the background of many war movies because they are a lot cheaper than using CGI and they look so realistic from a distance.
Of course when it comes to tie in models the film industry makes a lot of money this way and many Scalextric sets have been sold based on movies such as Batman Begins, The Simpsons, Transformers , Spider-Man and of course the classic Knight Rider and people are very much interested in buying those things. This kind of proves that not only to film makers rely on the models to produce the movies but rely on the sales of them to actually make a bit of money from the movie or franchise.
Models are still very important when it comes to shooting a movie and help film makers to see how things are going to work out. This is simply because one thing timed wrong is going to cost millions, testing using models is always a good idea.
