Why is chennai registered cars are cheaper compared to cars from other districts with TN?

Hey guys. I am from near coimbatore, about to buy my first car before the new tax regime comes into effect. While searching for some good second hand options. I find a pattern that vehicles with chennai registered number plate is usually priced lower than the ones from other districts. And the price of vehicles registered in Coimbatore in particular is very high compared to ones from Chennai. Are the people in any way driving cars different there in chennai for it to be priced at a discount? Also, most of these listings seems to show that there are no flood damage too. So, I'm genuinely thinking so hard to come up with an answer, but my pea sized brain is not able to understand this logic 😕