I'm going to ask about my old car after my dad just gave me a new one.
Why do you want to know about your old car?
I want to know if my old car is still ok and if it's still at the back of the house.
While there's nothing wrong with worrying about your possessions, asking about your old car so soon after getting a new one from your dad may make you appear ungrateful. You should maybe wait a little bit before bringing up the topic of your old car so your dad doesn't think is gift is unappreciated.
Can't I ask about my old car if I want to?
Of course you can. You can start the conversation off reminding him how grateful you are before you ask about the old car.