New car vs Used car?

I am in much need for a new car. I have heard that it is easier to get a new car than a used car. Is this true? I have a car now that basically needs a new engine and I just don't wanna put up with it anymore. We still owe abot 5,000 on it. I wanna trade it in, which I checked I could, and I have about 1,000 to put down on another car. I know my credit score is not the best but we also have a co-signer with good credit. My father seems to think I should just get a new engine. We have been wanting a new car anyways and what are my chances of getting a new engine or rebuilt one in a timely manner. I work and have two kids so I need my car bad. What would you suggest I should do?