The Back to the Future time machine wasn’t always going to be a DeLorean. Sadly, it was going to be something much less interesting, a choice that, if kept in, would have made the movie dull.
Bob Gale told CNN, “Way back in that second draft, it was going to be a ‘time chamber,’ not unlike a refrigerator, and Doc Brown had to carry it on the back of his truck. When we started figuring out how to make the movie, Bob Zemeckis had a flash of inspiration and said, ‘It should be mobile. It should be built into a car. It could be a DeLorean.’”
An immobile machine is what we’d seen in so many time travel movies, from decades before to even in the ’80s itself. In Bill & Ted, the time machine is a phone booth. The movie is fun because of its wacky characters and the crazy scenarios they’re put in, but the phone booth time machine isn’t all that fascinating, other than being a relic from its time.
The TARDIS from Doctor Who is much the same way, with the time machine appearing as a police call box. While it’s much more advanced than what Bill and Ted’s contraption could do (more of a spaceship than a time machine), it was still somewhat limited. A chamber as a time machine for Back to the Future would have turned the film into something completely different. So many scenes wouldn’t exist at all. Time really would have changed.
Having a cool car as a time machine prevented Back to the Future from feeling like another schlocky time travel movie. That clichéd sci-fi approach would have limited the film’s appeal to a mass audience. The DeLorean made time travel cool.
As Doc Brown says in the finished film the first time we see the DeLorean in the Twin Pines Mall parking lot, “The way I see it, if you’re gonna build a time machine into a car, why not do it with some style.” The DeLorean is the perfect time machine because it becomes an active participant in the plot. There’s only so much you can do with a boring, passive, immovable box. The DeLorean was its own character. It had its own fascinating and realistic design. A fast car makes everything so much more exciting.