Ah! Classic cars! An essential part of the plot of so many films!
But what is a classic car? According to my dictionary, it is one which sets a standard, or embodies the better qualities of its genre. Contrary to popular opinion, a car does not acquire classic status merely by being old. A Rolls-Royce "Silver Ghost" 40/50 is classic, as is a Lancia Lambda or a Chrysler Charger E49. A Napier 40/50 is not a classic, any more than an Austin Heavy Twelve or a Vauxhall Viva. They are just old. And naming a car "classic" is a clear admission that it is not. Who remembers the 1961 Ford Classic? I rest my case.
Classic cars are common in films, sometimes as props and extras, sometimes as stars. "Christine" comes to mind, but a 1958 Plymouth, while likeable enough, is not a classic. Hundreds of thousands were made, too many with an anaemic sidevalve engine. The Packard convertible in "Back to the Future" is definitely classic. So are the Ford GT40 and the Lancia Fulvia HF in "Un Homme et une Femme", which won an award at Cannes in 1966. The Wolseley 6/80, used as a police car in so many 1950s British films is not classic, and works much better with a Holden engine in place of the horrible unreliable thing with which it was made. The Alfa Romeo Montreal in "The Marseilles Contract"? Hard to say, but probably a classic, as was the Alfa Romeo Duetto in "The Graduate"and "Day of the Jackal". So was the 1956 Thunderbird in "American Graffiti", and the Series I E-Type in "Vanishing Point". The Pontiac Firebird used in various Burt Reynolds movies was not.
Classic cars are not always treated well on the screen. Does anybody really believe that a 1960s Aston Martin DB5 can keep up with a hard-driven Ferrari 355? In the fragment of "Ferris Bueller's Day Off" that I made myself watch, there was a Ferrari 250GTO. I was expected to believe that a car of which only 39n were made and which was worth about a million pounds in the eighties would be available for an adolescent to drive, and just in case that wasn't enough of an insult to my intelligence, it fired immediately on all cylinders from cold, and it was obvious from the sound that it had only eight of them. Sorry, but a Ferrari should sound like a Ferrari, not like a Chevrolet.
When a car is a star, it is not necessarily the classic car which achieves stardom. The brief appearance of the Thunderbird in "American Graffiti" went almost unnoticed among the cosmetically-enhanced and musclebound American Ordinaries which dominated that film. The most conspicuous car in "Back to the Future" was a DeLorean, an inferior imitation of the Renault Alpine (definitely a classic). Cars are often used to say something about a character. Colombo's Peugeot 403 convertible and Cannon's Continental Mk IV (See? Not all of them are driven by pimps.) are examples, as are John Steed (vintage Bentley) and Emma Peel (Lotus Elan) from "The Avengers". The Hillman Avenger, incidentally, is not a classic. And why isn't James Bond driving a TVR? It's a bit more British than an Aston these days.
Some films, unintentionally, have mostly classic cars, like ""The Marseilles Contract", apart from the Montreal and the inevitable Porsche 911, has Citroen DS21s and a Renault 16. Remember when French cars really looked and felt French?
So, in conclusion, I would say thet while classic cars are shown a lot in movies, a lot of the supposedly classic automotive performers are impostors. S-type Jaguars, driven by copper and villain alike in so many British films are classic, but Cortinas ("Get Carter") and Mustangs are not. Minis, by which I mean the genuine Issigonis-designed Mini, not the de facto 2-series BMW of today are classic. Fintail Mercedes are classic. Most American cars are non-classic, as are most Japanese cars in films.
Incidentally, one of the best car chases I have seen was in "The Burglars", and the two cars in that were definitely not classic, a Fiat 124 and a scruffy Opel Rekord.