Using highway mileage markers, I know that the speedometer on my pickup truck is slightly inaccurate, even though it is a GM product.
… by manufacturer, GM’s domestic products are the most accurate, and BMW’s are the least accurate by far.
In the U.S., manufacturers voluntarily follow the standard set by the Society of Automotive Engineers, J1226, which is pretty lax. To begin with, manufacturers are afforded the latitude to aim for within plus-or-minus two percent of absolute accuracy or to introduce bias to read high on a sliding scale of from minus-one to plus-three percent at low speeds to zero to plus-four percent above 55 mph. And those percentages are not of actual speed but rather a percentage of the total speed range indicated on the dial. So the four-percent allowable range on an 85-mph speedometer is 3.4 mph, and the acceptable range on a 150-mph speedometer is 6.0 mph.
This was never a big deal to me, as I usually travel close to the speed limit on highways, and a few miles per hour, one way or the other, was no big deal. Looks like that’s changed:
The Oklahoma Highway Patrol is pulling people over who drive under the speed limit in the left lane.
“If you’re driving 65 or slower, you have to be in the right lane. Are you aware of that law?”
Uh, I thought I was aware of that law. But evidently not. It was my understanding that if you were traveling the maximum posted speed limit, you could use the left lane. So, I checked the applicable wording:
47-11-301 (b) Upon all roadways any vehicle proceeding at less than the normal speed of traffic at the time and place and under the conditions then existing shall be driven in the right-hand lane when available for traffic, or as close as practicable to the right-hand curb or edge of the roadway and may be temporarily driven upon the right-hand shoulder for the purpose of permitting other vehicles to pass. This subsection shall not apply when overtaking and passing another vehicle proceeding in the same direction or when preparing for a left turn at an intersection or into a private road or driveway.
The statute contains no mention of speed limits at all, yet the accompanying video shows an OHP Trooper stopping a motorist for traveling 62 mph in the left lane. If the accepted inaccuracy of a speedometer is 3.4 to 6 mph, an astute driver might believe to be traveling OVER the speed limit, but actually be moving at less than 62 mph and warranting a traffic fine in excess of $200.
But what if your speedometer is inaccurate in the other direction? You think you are driving 65 mph, but actually traveling over 68 mph? You are not only violating this law:
47-11-801 … the limits specified in this act or established as hereinafter authorized shall be maximum lawful speeds, and no person shall drive a vehicle on a highway at a speed in excess of such maximum limits:
But also this one:
47-11-901 (a) It shall be deemed reckless driving for any person to drive a motor vehicle in a careless or wanton manner without regard for the safety of persons or property or in violation of the conditions outlined in Section 11-801.
Therefore, the only way to travel an Oklahoma highway in the left lane and not violate the law is to be turning left or passing a car going significantly less than the speed limit.
With lawmaking logic like this, where everyone is a criminal, is it any wonder why our prisons are overflowing?