I would like to return the rental car.

我来还租的车。

May I get the keys and see some ID?

请把钥匙给我，并给我看你的证件，好吗?

Let's go outside and take a quick look at the car.

我们到外面去把车子检査一下吧。

I need to fill out a report on the return condition of the car.

我需要填一份车子“归还车况”的报告。

Make a note if you find any dents or scratches.

要是你找到任何划痕或刮伤，请注明一下。