Don't Look a Gift Horse in the Mouth(don't complain about something that is given to you)
How are you enjoying your car, Mike?
It's not bad. It doesn't look like much, but at least it's transportation.
Didn't your dad just give it to you outright?
Sure, but it was his old one. What I really wanted was that sleek sports car I was looking at the other day.
For gosh sakes, Mike. Don't look a gift horse in the mouth. If I were you, I wouldn't complain. Look at me. I'm still getting around on my bike.
I guess you're right. I shouldn't find fault with something I got for nothing.
Exactly! You'll have the car you want some day. Just be patient. All you have to do is get yourself a job and save money.
much = たいしたもの
outright = 無条件に
sleek = ほっそりしたスタイルの
get yourself a job = get a job