I remember repeatedly borrowing this book from my local library back when it came out, and forgetting that the book irritated me, not even half way through it. In short, I couldn't stand either character. If I remember correctly, Nancy was a nag and Mark was an inconsiderate asshat. There was nothing whatsoever to like about these two, and of course, going on a long road trip just made things worse for me in my mind. If you're thinking the cute, nemesis-like friendship between Harry Burns and Sally Albright in the film "When Harry Met Sally"... think again. These Nancy and Mark fell short of trying to entertain, and weren't the least bit amusing even though I'm sure the author tried his best to incorporate humour with a sparring almost-couple.
I kept borrowing it from the library because I remember the summary caught my attention because the concept was great, but taking it home each time and being disappointed it was the same book I hated.