Measuring a car's speed by the miles it covers in an hour is as obsolete as the buffalo nickel. Drivers need a speed measurement that reflects our go-anywhere-fast lifestyle. We must replace miles per hour with feet per second. Before it's too late.

Next time you're out driving in your Plymouth Lancet or Lamborghini Inspector Rebus or whatever, look at the speedometer. What's the number read? 30 miles per hour? 40 miles per hour? 90 miles per hour? 175 miles per hour? What do those numbers even mean?

Miles-per-hour numbers have little to do with our bodies' sensory response to forward motion. As much as the inner-ear's spacial-orientation center knows, we could just as well measure a car's speed in degrees Kelvin, or microfortnights or Hoppus feet.

Add to that, every car built since the late 1980s feels slower than the speedometer's reading suggests. You know it's true. Just think about how often you've looked down and been surprised at the number on the speedo, then realized you're at the laundromat.

Still, we measure speed in miles per hour because that's what all the speedometers say (at least in the U.S.). But why?

Back in the 19th century, stagecoaches ran on a timetable derived by calculating how long it took a coach to travel the distance between violent armed holdups. When trains came along, we employed the same measurement, even though some people back then thought passengers would suffocate if a train went over 20 mph. Those people must have felt pretty silly sitting on board in their diving helmets when trains started hitting 30, 40, 50 mph.

But now, as cars travel independently of fixed stations or stages, the quantity of ground we cover in one hour seems far less important than how much ground we're covering right this second. Especially when the guy in front of us just jammed on his brakes to avoid a hedgehog, while cueing up Scorpions' "Rock You Like a Hurricane" on Spotify.

Imagine yourself whooshing down a highway, not at 68 mph, but at 100 feet per second. Count one-Mississippi and you've just dispatched the span of 100 foot-long hot dogs. Count 10-Mississippi and you've just screamed past the Eiffel Tower, laying on its side. Count 100-Mississippi and you've just stopped to ask some guy with six teeth and a hook arm how to get back to the interstate.

Make sense now?

Slapping a number on something indeed affects our perception of its intensity. In Ireland a few years ago, amid a controversial switch from Imperial units to metric, a judge reduced a speeding charge against motorist David Clarke, who'd been busted flying down a road in County Donegal at 180 kilometers an hour. Clarke was about to lose his license until the judge realized his speed didn't look quite so bad in miles per hour, so he let him off with a warning.

Of course, if Clarke had been caught going 164 feet per second, he'd be kneeling on the floor of his cell in Kilmainham Gaol warming his hands over a whale-blubber candle. OK, that's probably not the best example.

But perhaps we'd forge a closer connection to speed if we considered how many feet we're knocking off at each tick of the pocketwatch, instead of how far we can drag a coach full of dowagers across Oklahoma in an hour. Maybe then we'd prove ourselves capable of driving as fast as our technologically advanced vehicles would like to take us, without once in a while smashing each other into short stacks of buckwheat pancakes.

Anyway, it's time for a change. This old, miles-per-hour thing is rapidly turning quaint. I don't know about you, but lately I've found myself caught between the present and the past, saying things like, "Here, Martha. In the span of one hour, we shall navigate 65 broad miles! Is not the caprice of mankind terribly keen?"