at 27% you will never be upside down. this little car will hold its value better then any car out on the market. [ok so it will remain in the best of the best] I sell 5 year old rav4's with 80k miles all day long for 17K$ that had a sticker for 23$ new. your C will hold its value
As was intimated, just check the trade-in/resale values on, for example, a 2010 Prius at www.kbb.com to get an idea of how well Prius retains. I didn't put anywhere near 27% down on my c, but I suspect I'll not become upside down given how little I drive in comparison to the norm.