I think this is the most famous tracking shot in the history of the movies: the opening scene of Orson Welles's "Touch of Evil". But I'm convinced that the shot is famous for all the wrong reasons.
It's famous mostly because it's such a technical marvel. It's impressive that Welles was able to coordinate and choreograph so many elements and get them all moving at the right time.
But the most important criteria for any shot is whether it's the best choice for telling the story that's being told. And people seem to get hung up on how impressive this tracking shot is, and that distracts everyone from talking about how well it serves the story point being told.
If you picture in your mind this scene full of different shots cut together, you'll realize that if it were assembled that way, you would quickly lose track of which car was the one with the bomb in it. Even if you only showed one car the whole time, I still think that if you did it all in cuts it would be confusing and not nearly as powerful. You would never be sure if, after a cut, you were looking at the same car as the one that we saw at the opening. When it's all one shot, you never lose track of where the car is in relation to the camera and our characters. You never have the audience getting distracted by trying to figure out which car is the one we're supposed to be following. The viewer can therefore focus on the characters and the story being told.
There are other ways to accomplish this same thing, of course: make the car and/or it's passengers distinct enough visually that we would always recognize them, but still, that's not nearly as elegant an approach and besides it would be transparent as to exactly what the film maker was doing, which would be distracting.
Also the tension of the car being where we can see it, then out of our frame of vision, and then back in the frame creates great tension. It makes us nervous when we can't see the car and we don't know exactly where it is. It also makes us nervous when we see it near groups of people. We have no idea when it's going to explode. And again, I think much of this would be lost if we were cutting around.
This version above is from the newly-released version that hews closer to Welles's vision of what the movie ought to be. If you've ever seen the original released version, you may remember that this whole sequence was covered with opening titles, as well as a piece of music written by Henry Mancini. It was Welles's wish that the music during the opening be source music as it is in the version above. The reason for this is very clear, and it's a good one: Welles was trying (I assume) to show the difference between the two sides of the border (one side is America and one side is Mexico) and the source music coming from different nightclubs and cars helps to emphasize the difference between the two sides of the border. The film is all about the difference between the areas north and south of the border and the struggle of the man and wife (who are each from a different side of the border) as they struggle to stay together and not be torn apart by the whirlwind of events that overtake them. So thematically it fits because it's emphasizing the difference between the way the two different areas sound. Also using source music helps it feel like a real world and a real space instead of a studio backlot.
As I always say, one of the most powerful ways to start a movie is to pose a question that the audience wants an answer to. This always helps create interest in the audience and compels them to follow the story. So right away we want to know: when will the bomb go off and what will happen when it does? And we also want to know who planted it and why?
The last thing that's impressive about this shot is how much storytelling is compacting into this one shot and how effortlessly it's done. Here's what you find out: these two (Heston and Leigh) are newlyweds. They come from opposite sides of the border. And he's a detective who breaks up drug rings. He's currently fighting against a drug smuggling operation called the Grandi family.
If you look at the Three Act structure template, Act One is defined as "The exposition (or information) you need before the actual story can start". When the audience has all the information they need about a character's everyday world, then the "inciting incident" happens and their world is thrown out of balance. Then the whole movie is (usually) watching them try to put their life back to where it was before it got messed up.
Well, the explosion at the end of this shot is the "inciting incident"; it leads to Welles's character showing up a minute later and he throws Heston and Leigh out of whackl pretty quickly. So therefore this entire camera move is the Act One of "Touch of Evil", which is pretty impressive. That has to be one of the shortest Act Ones ever, and definitely the only one I know of that's all one shot.
Anything you can do to shorten the exposition your audience has to sit through in the beginning is always advisable and your audience will appreciate it. We all like to get to the action and conflict as soon as possible. And whatever information you're going to make the audience sit through, you would be well served to find a way to make it entertaining as Welles does here right from the first frame of the movie. Bringing conflict and drama into your movie from the opening shot of the film is always a great way to start a film.
Also, I can't help but point out how much depth and space Welles was careful to pack into this shot. This whole movie is made with a great sense of depth: characters constantly moving through the frame from the foreground to the background; characters leaving the frame and their shadows passing through the frame after they've left, etc. The film, now fifty years old, feels like it's got camera work that is still ahead of it's time - very few directors seem interested in using the camera to tell the story in new and exciting ways these days.
There's a new 50-year anniversary set that has three versions of the film, including the one that's "closest" to what Welles might have wanted (but we'll never know for sure) including a recreation of a 58-page memo he wrote after seeing the studio's cut of his movie. "Touch of Evil" is a strange movie on many levels. It has a lot of elements that are really laughable by today's standards. It certainly won't be everyone's cup of tea, but there is definitely a lot to be learned for anyone interested in studying film, staging and how stories can be constructed.