OK, since my publisher informs me that sales of Driving Perfection, or How, If Everyone Drove More Like Me, The World Would Be Much Better Off, are not as brisk ask demographic surveys initially projected, I must assume that my extensive instructions/recommendations are not reaching the masses (great unwashed though they may be). Therefore, I shall obviously have to dish out my nuggets of wisdom piecemeal.

Today’s topic of amazement: Proper spacing of vehicles on the country’s thoroughfares.

The “official” line is that you must leave 1 car length’s distance twixt you and the car in front of you for every 10 miles per hour you are driving. Thus, on a city street – according to “the rules” – you must leave 3.5 car lengths between the front bumper of your car and the rear bumper of the car immediately in front of you. And, extrapolating this out further, if the interstate speed limit is 70mph, then there should be a full 7 car lengths between you and the car immediately ahead of you.

Stop and think about that. Well, don’t stop if you’re reading this while driving on the interstate – but that’s another problem altogether – you know what I mean…

So, let’s first tackle how much distance this actually translates to in feet/meters.

There was a study done in Portland, Oregon to find the average length of a car. They wanted to see what size parking spaces would be needed to accommodate people.

They measured 390 vehicles (front bumper of the body to the rear bumper) and found the average length of 13.51706036745407 feet (4.12 meters). This is the average size for midsized sedans/coupes (combustion engines).

A vehicle over 16.40419947506562 (5.0 meters) would be considered a large sized truck or SUV (usually commercial sized heavy duty diesels, like the Ford F-350-450).

Thus, on the average city street, where 35mph is the posted speed limit, you must maintain at least 47.309711286089 feet (or 14.419999999999929 meters, assuming anyone outside of the US is reading this) between you and the car in front of you. A nearly-5-story building should be able to lie down (assuming it’s exhausted) between you and the car in front of you at all times – at least when the wheels are turning (I’m quite certain someone, somewhere, has codified the mandatory distance between idling vehicles at a stoplight, but I will look into that later).

Now, projecting this out to the interstate, you have to allow for 94.619422572178 feet (28.839999999999858 meters) distance between you and the guy in front of you. Ideally, he and you have coordinated ahead of time, setting your cruise controls to pace at precisely the same speed throughout your trip, so that you’re not constantly fumbling around with your Home Depot laser measuring device to ensure you’re not violating local constabulary mandates – which surely vary from city to city, county to county, as you cross over from smooth asphalt surface to the less-well-funded adjacent county’s crumbling concrete road surface.


Does ANYONE on the planet actually follow these laws? I highly doubt it. Yes, most states (if not all – sorry, I haven’t done all my homework) have minimum-car-length-distance numbers recorded in their statutes, and doubtless all local and state law enforcement officials have them memorized.

I know that somewhere in the distant past, decades ago, when I took Driver Ed in high school (you know they don’t offer that as part of your mandatory curriculum in most states anymore – it’s almost always private, cash-out-of-your-pocket-taught-by-off-duty-law-enforcement companies?), I took a written test where I had to select from narrowly-varying distances the correct spacing for highway driving.

And all of that assumed a lack of cumulus clouds in a tri-state area radius around your vehicle. We won’t even discuss rain, snow, hail, fog, or humidity – those are all saved for a later rambling…

No. 99.99% of drivers don’t know these laws. Virtually all spacing of vehicles on local and long-distance thoroughfares as gauged on an individual basis, by drivers using their innate common sense. Yikes.

We all know that, if vehicles in the left lane are more than 1.5 car lengths apart (you do the math), that is perfect justification for vehicles in the right lane to veer left in order to pass the nonagenarian ambling in their Rambler ahead of them.

And the ones we REALLY get pissed at are those drivers who – permanent residents of the left lane, as we have discussed before – HAVE memorized each state’s car-spacing-sacred tablets, and have allowed for a gap large enough to swing a battleship on wheels entrée into the space in front of them. Thus, vehicles are ceaselessly veering in front of them to join the speedier crowd in the left lane.

And do these law-abiding-to-the-micron-letter-of-the-rules drivers take the hint? Perhaps they have allowed for too large a gap, and should close the distance, thus preventing those insipid right-laners from jumping in front of them? No. They either hit their brakes, turn off their cruise-controls (thus throwing off your previously-agreed-upon-arrangement), or simply lift their foot off the accelerator, ensuring that they drift far enough back from the new vehicle ahead of them that they don’t clip that 10-story edifice that might recline in front of them at any moment.

Once again, your blood pressure increases, as you see no solution in sight. Unless, of course, there’s some lowbrow in the RIGHT lane having his wife read him the iPhone-friendly online version of your current locale’s car-length-spacing rules and regs to him. Then it’s the whole passing-on-the-right thing.

A topic for another day.


c'est moi