Editorial policy

Every figure is dated and sourced

The calculator does not contain hard-coded numbers. It reads a single dated file, currently version 2026-09, compiled 2026-08-30, holding 97 published figures. Each one records its value or its range, the date it was taken, the source it came from, how often it needs refreshing, and how much confidence it deserves.

All 97 are listed on the assumptions page, and every result shows the subset it actually used. That list is observed while the calculation runs rather than written by hand, so it cannot claim a source the arithmetic did not use, and it cannot leave one out.

Ranges where a range is the truth

Interest rates and insurance premiums are published as ranges, never as one number. A credit band does not produce a rate, it produces a spread, and an Ontario insurance premium for the same driver varies more between insurers than most of the other lines on the page vary at all.

Showing a single figure where the underlying data is a band would look more authoritative and be less true. Where we are estimating rather than calculating, the page says so on the line itself.

What we refuse to publish

Some figures have sources that genuinely disagree. Average new vehicle transaction price is the clearest case: three reputable sources give three materially different answers, and picking one would be choosing a number rather than reporting one.

Those figures are marked do-not-publish, and today 3 of them are. They are named on the assumptions page without their values, because the note explaining why a figure is contested spells out the contested numbers. This is enforced by the code rather than by care: any page that tries to read a withheld figure fails the build.

When figures get refreshed

Each figure carries its own refresh cadence, because gas prices and the federal luxury tax threshold do not move at the same speed. The file is versioned by month and every version is additive, so a shared result from an earlier vintage still says which vintage it came from.

The version string is in the footer of every page on this site. If it looks stale to you, it probably is, and we would like to hear about it.

Corrections

If a number here is wrong, tell us at hamata.mike@gmail.com and include the page and, if you have one, the source you think is right. We would rather hear it from you than leave it up.

What happens then:

• A figure that is wrong is corrected in the assumptions file, which changes every page that reads it at once. Nothing is patched on one page and left standing on another.
• A calculation that is wrong gets a failing test before it gets a fix, so the same error cannot come back later.
• Where a correction changes an answer materially, the change is noted on the page rather than made silently.
• Where two sources disagree and we cannot resolve it, the figure comes down and joins the withheld list until we can.

Who writes this

The calculator, the figures and the guides are the work of Mike Hamata. Guides carry a byline and a last-reviewed date. Nothing on this site is published anonymously, and nothing is published by a contributor whose name we would not put on it.

Independence

Nobody pays for coverage here, because nobody pays us at all. No dealer, lender or insurer has any influence over a figure, a verdict or a guide, and there is no advertising to have influence with. The arrangements, including the ones we might have later, are on how we make money.