As a monthly check-up, I'm updating my car value here. I drove quite a lot last month and my odometer now reads 35,400, or 1,300 miles for the last 30 days.
Here is the valuation compared to my first checkup back in October.
Edmunds.com
Trade-In Value: $11,353 (October = $11,711, Change = $358)
Private Party: $12,864 (October = $13,172, Change = $308)
Dealer Retail: $14,514 (October = $14,784, Change = $270)
NADAGuide.com
Average Trade-In: $10,275 (October = $10,625, Change = $350)
Average Retail: $12,325 (October = $12,775, Change = $450)
It appears that the monthly depreciation of my Camry is very mind, averaging barely more than $100 per month with 1,000 miles/month usage. So it seems reasonable for me to depreciate the car by $150 per month in my accounting rules.