Valgrind was released in 2002 to immediate celebration. It was available and surely known to the team. All they needed to do was write a unit test that loaded and instantiated those vehicle files and run it with "valgrind" in front of the command line.
I tried to use Valgrind to catch pretty much this exact bug 20 years ago, and it was nigh impossible. If you call any 3rd party code it'll have flag tens of thousands of false positives that you have to sift through. And that was on a small game engine, I can't imagine running it on millions of lines of code.
I don't know whether Valgrind ever gained support for any of the GTA target platforms. It wasn't available on Windows for a very, very long time.