Johnny Tran: I'll see you in the desert next month. Be ready to have your ass handed to you.
Dom: You're gonna need more than that crotch rocket.
Johnny Tran: I got something for you.
Toretto: Ask any racer, any real racer. It doesn't matter if you win by an inch or a mile, winning's winning.
Dom: You can have any brew you want... As long as it's a Corona.
Dom: I live my life a quarter mile at a time. Nothing else matters: not the mortgage, not the store, not my team and all their bullshit. For those ten seconds or less, I'm free.
Letty: You want a piece of ass, go to Hollywood Boulevard. You want an adrenaline rush that'll be two large.
Dom: I'm not running!
Brian: I just need some more time.
FBI Officer: If you want time, buy the magazine!
Jesse: Hey, you just can't climb in the ring with Ali 'cause you think you box.
Answer: There are two ideas of why the police did not come around. Firstly they might have found out after the car chase that Brian was an undercover cop so it would be more effective to allow him to try and discover information instead of going around and arresting Dom. The other idea is that the police might not have enough to arrest him. Dom was not the one driving when they found him and other than racing, it might be tough to arrest him.
Lummie ★
Cops are usually completely unaware of an undercover cop's identity. The more, realistic reason is that the cop didn't ID Dom and since Brian's car was later destroyed, there's nothing for them to investigate. Afterwards, they might ID Dom, but there's an investigation on him, so they'd leave him alone.