"While speedometers are calibrated to fudge the numbers a little, odometers are designed to reflect accurate mileage, Tetzlaff says."
"The odometer, which directly reflects what the sensors are recording, doesn't have the same built-in inaccuracy as the speedometer. If your speedometer is off, it doesn't necessarily follow that the odometer is inaccurate too."
https://www.theglobeandmail.com/globe-drive/culture/commuting/why-you-may-not-be-driving-as-fast-as-you-think/article11487709/