Think Pieces

Michael's thoughts on the auto industry, its products, and/or this website.

Why yet another vehicle pricing site?

After all, there were hundreds already.

Well, TrueDelta is unlike any other vehicle pricing site, beginning with a focus on clarifying the differences between vehicles. Hence the name: in scientific notation the Greek letter delta stands for a difference. The goal: stats that are at once precise, thorough, readily comparable from car to car, and easy to connect to real life. With regard to prices, this means providing true "apples-to-apples" comparisons, something that had not been done before.


I first recognized the need for a better way to perform vehicle price comparisons while writing car reviews for Epinions. Professional auto reviewers (which I am not) tend to compare prices in one of two ways. Sometimes they compare base prices. Other times they compare "as-tested" prices. Either way, the cars being compared are often much differently equipped.

In my reviews, I attempted to perform more thorough price comparisons. Using various websites, I equipped vehicles as similarly as possible then wrote up the results. With these sites, each car or truck had to be priced separately, with much attention to option packages, prerequisites, and illegal combinations. Some sites automatically presented this information when I clicked on an option. But even on these, every time I clicked on an option I had to wait while the necessary calculations and changes are made. Very tedious. Even though I didn't try to adjust for features that remained unshared, this section often took me an hour to write.

There had to be a better way. So, in the summer of 2004 I taught myself to program, and that fall launched TrueDelta's price comparison tool.

Innovative aspects

To minimize the time and effort required, I designed the program to automatically sort out prerequisites, included features, and illegal combinations in a single pass.

Existing pricing websites also required the user to select a trim line and then to select option packages. The SE, SEL, or SES? The SE? Well, then, the Preferred Package, Premium Package, Luxury Package, or none of the above? Learning the contents of these trim lines and packages often required a great deal of clicking and reading.

So, to save time and facilitate comparisons, I also designed TrueDelta's price comparison program to automatically select trim lines and option packages. The user only has to select easily understood features like power windows, leather upholstery, and alloy wheels.

To enable even quicker comparisons, I included "minimize" and "maximize" modes to automatically configure (relatively) stripped and loaded vehicles.

Finally, I realized that many features remained unshared no matter what. So I determined standard values for each feature based on the low end of what vehicle manufacturers typically charge and adjusted prices accordingly.


The value of the resulting vehicle price comparison tool becomes apparent when applied to an example: the Pontiac Solstice vs. the Mazda MX-5.

In Car and Driver's October 2005 comparison, a bar chart suggests a $5,000 price difference. They compared a base Solstice (no other trim lines were then offered) to an MX-5 in top-of-the-line "Grand Touring" trim (four less expensive trim lines are available). Their price comparisons exclude the cost of options that do not contribute to performance. But they do not consider that a less expensive trim line might provide equivalent performance. Both cars were similarly loaded, but in the Pontiac's case optional features were separately priced rather than included in the base price of the trim line, so their cost was not included in the comparison. Clearly not a fair comparison; just an easy one to perform.

Car and Driver tested loaded cars. With TrueDelta, selecting the MX-5's six-speed manual (and thus its top trim lines), both cars' optional audio systems, and the "maximize shared features" shortcut to closely approximate the vehicles they tested yields an MSRP difference of $1,615 in the Pontiac's favor. Adjusting for feature differences cuts this to $1,480, less than one-third the difference implied in the magazine.

Car & Driver generally suggests that true enthusiasts don't need leather and other luxury features; hence the inclusion of only performance options in its price comparison. I further wonder why the Mazda should have a six-speed manual transmission when the Pontiac is only available with a five-speed. Going with the latter opens up the MX-5's less expensive trim lines. Doing this and specifying "minimize shared features" yields a difference of $85, now in the Mazda's favor. Adjusting for feature differences enlarges this advantage to $270. We're now $5,270 from the number implied by Car and Driver.


You might want a car equipped somewhere between these two extremes. That's why TrueDelta, unlike other sites that provide price comparisons, lets you specify the features yourself. And, if you're a panel member, you can even specify how much various features are worth to the person that matters--you.

But no matter how you use TrueDelta's price comparison tool, you can count on a more relevant comparison than you'll get anywhere else.

Thanks for reading.

Michael Karesh, TrueDelta

First posted: September 4, 2005
Last updated: November 15, 2006