If the price of an imported car you want to buy is say $25000 today and then it gets a tariff of 50% on it, it will now cost you $37,500. Right?

Not necessarily. Maybe the manufacturer cuts the price. Maybe the manufacturer goes to its government and says "Please subsidize my sales to the USA." Or, maybe the car doesn't sell here anymore and the company sells it in India and India exports a similar vehicle that isn't subject to tariff.

Would the local car sell for $37.5? Why would it? You assume that only one local maker "wakes up." Competition drives price to cost. When TWO local producers wake up, they compete on price. You pay more than $25k, because costs are higher here, but you don't pay the tariff, which is a protectionist measure intended to boost local sales, not raise revenue.