Grammatical reason why "using car" is incorrect

Question

Higher prices would not stop them from using car as their first choice of transportation

What's the grammatical reason that this sentence is incorrect, and "the car" or "cars" has to be said instead of simply "car"?

Answer 1

This is getting to how we express levels of abstraction and collective nouns and categories.

As the quote stands, the word "car" is referring to something non-specific and without quantity or difference. That is, it is referring to "car" in the abstract rather than in the specific.

Compare that with the following.

Lower prices do not encourage them to use transit as their first choice.

Lower prices do not encourage them to use a bus as their first choice.

Lower prices do not encourage them to use the Bloor Subway as their first choice.

(Bloor is a street in Toronto, Canada. There is a subway that runs parallel to it.)

Here "transit" is an abstract thing. That is, it is a category of transportation. "A bus" is a thing, but not a specific thing. It is more specific than transit, but still not specific to a particular bus. "The Bloor Subway" is a specific thing.

Treating "car" as an abstract indefinite thing is unusual. I'm not sure whether it is grammatically correct or not. But it sounds very strange. If you were in fact in a car you would be in a specific car. You would not ordinarily refer to this as "I am riding car." Where if you were on a bus you could say "I am taking transit." We don't usually use "car" as an abstract indefinite category in this way.

You might want to say something like "transportation by car" or some such rather than "car." That is, you might choose some abstract phrase that indicates using a car but not a specific car.

Answer 2

At first look, it could seem like the word 'car' is missing an article or a possessive pronoun, for example, "a car", or "their car". In most contexts, the grammar of your example would be considered incorrect.

But, depending on the wider context, your example might be acceptable as it is.

It sounds like the quote could be referring to a large cohort of people - perhaps the results of a survey. They could have been asked how they travel - by car, by bus, by train etc. When we speak about these as modes of transport, they don't need an article. If 'car' didn't need would an article or determiner in the question, nor would it in the answer or any subsequent references to that answer, for example:

Person A: What do you think is the best way to travel to work - by car, or by bus?
Person B: Car.
Person A: Why did you answer "car"?

In such a context, where you are speaking about the responses of a large, impersonal group, it would also be wrong to assume that every person who travels by car travels in a car that belongs to them, so "their car" isn't really appropriate anyway.