See attached.
I don't think the nice-looking graph is of much value without other metrics thrown in, such as model (280 does better than 230 but not always) and some kind of assessment of condition.
As with a lot of data, throw out the outliers (high and low) and look at a trend line, and if you do that from a seat of the pants analysis, I see prices moving from the $50K to $70K range in 3-4 years. But, without that condition assessment, it's all just a bunch of numbers...