By far, this is not my favorite episode. I can't believe the police would follow Simon just because they thought this was a stolen car and that he was going only 10 mph. I also can't believe that Simon wouldn't pull over when the police, with their lights going, are behind him. It all seems a little far-fetched.
I don't know if Jeremy went about it the right way, but I do think that he has the right to ask for the engagement ring back. It was a gift expressing engagement to be married. If Lucy's not engaged to him, she needs to give it back. It's the only fair thing.