Doing a quick check on Kelley Blue Book's website
, these are the values for various years of the Toyota Camry. This is for the Camry LE 4 cylinder with an automatic transmission. Standard features and 12k miles per year were the baselines.
2008 $23,000 (dealer prices)
These are their recommended purchase prices. After the first two years it becomes rather linear, a little under 8% of the new car price per year. The first two years are about 10-11% of the new car price per year. Keep in mind this is a quick, off the cuff run of the numbers from one website for one vehicle. It's not a definitive resource, but it's a reasonable guide.
Unless you are talking about a car packed with luxury items, the standard tale of depreciation over the first couple years is overblown. For a standard model without a lot of bells and whistles, the depreciation in those first couple years is more but not significantly more. Start adding in what you'd pay new for things like color highlights, interior walnut trim, and multi-CD changers, and you will see the price of a new car rise quickly compared to what it would be worth in a couple years.