I have a similar situation but his interest is in animals and not cars.
Almost at 18 month old we got Old Macdonald DVD from Kissongs and from there on everything for him is EIEIO.
I don't know if this is an issue but I am worried because my grandson dies for animals and books but even though he has cars he pay no attention to them. All he wants to know is the name of the animals in spanish and english and get books on animals. I this ok or I have to insist so that he plays with other things. When my sons were small I worked and didn't have time to observe this.
I want to spend morre time teaching him all i can now because i am afraid that in a few months or years he will loose interest in learning.
The issue here is that we allways heard that all extremes are not good and if he onlly wants animal or car topics and nothing else we have to try to make it nice for him and play with other things.
NidaZafar, is he absorbed only with car toys or also books on cars and so on. Maybe if you start with books on cars then you can go to other books to capture his interest.
If you get good results try afterwards this books:
Brown bear, Brown Bear what do you see
Polar bear Pola bear what do you hear
and
Panda bear Panda bear what do you see