Over at GMInsideNews, Ghrankenstein recently posted an editorial on the biases of automotive information sources. He divides these into two camps: those that strive to make the car buying process rational, and those that assume it’s emotional. His point: the former camp overemphasizes criteria that can be reduced to numbers, while the latter overemphasizes the necessarily subjective driving experience.

He places TrueDelta in the former camp, while noting that I’ve written editorials acknowledging the value of each individual’s subjective experience. I found the entire editorial insightful, and couldn’t agree more with this characterization.

That said, I’d like to push a bit further. I post my own reviews at Epinions, but there’s a reason for that site’s name. They’re just my own impressions. I don’t believe any car is simply “the best.” As I’ve written in a second editorial, comparison tests necessarily assume certain criteria and weights, and there’s no “best” set of these.

But this doesn’t mean that the decision of which car to buy must be entirely subjective. Each person must decide what they care about, and how these criteria rank. And for some of these desired criteria it is possible to supply numbers. Some potentially critical numbers haven’t been available. TrueDelta will remedy this.

TrueDelta’s price comparison tool confuses many people. What sense does it make to give each feature a value, when the features aren’t available separately? Well, this tool seeks to determine the price difference that remains after the values of commensurable features have been removed, leaving “core models” that must be subjectively evaluated. (Don’t agree with some of the default values? Well, panel members can substitute their own.)

The real-world fuel economy survey seeks to produce more valid numbers than the EPA.

Finally, there’s reliability. One of my primary criticisms of Consumer Reports is that providing results in the form of vague dot ratings hinders trading off reliability against other criteria. Is one car’s superior driving experience worth the difference between a clear dot and a red one? It’s hard to say, because the dots are relative and encompass broad ranges.

Knowing that the extra emotional appeal of a car was most likely to cost 0.8 extra repair trips over a three-year period would make trade-offs between the two much more feasible. TrueDelta won’t argue you should necessarily buy the more reliable or fuel efficient vehicle. It will only provide an idea of the object of your desire’s tangible costs. Only you can decide whether these costs are worth it.

Overall, TrueDelta aims to provide facts that can be combined with a car buyer’s subjective evaluations of what each potential purchase is like to look at, sit in, and drive. It doesn’t aim to replace this personal evaluation, only better complement it to yield a balanced whole.