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Five Driving Mistakes You Don’t Know You’re Making

Posted in DIY, driving, Promoted, Safety by Kurt Ernst | April 1st, 2011 | 9 Responses |

The deer on the shoulder isn't impressed with your HID lighting.

Here’s the thing about driving: very few of us learned to drive from a professional instructor. If we did, chances are it was an “instructor” who taught driving as a sideline to his real career as a janitor, music teacher, or cop. I’d argue the point that most of these instructors, while proficient in operating a motor vehicle, never really learned to drive. My first lessons came in a dual-control equipped AMC Hornet, and I can say with absolute certainty that we never covered topics like threshold braking, understeer, oversteer or even accident avoidance. Until I started taking lessons on a track, most of what I learned was from either my mistakes or the mistakes of others around me, and that rarely ends well.

Even if you had the benefit of proper instruction behind the wheel, chances are good you’re still doing something wrong. Below are five common mistakes that I see even experienced drivers make, probably because they simply don’t know better. Correcting them won’t shave seconds off your lap time, but they might help you avoid an accident or a costly repair bill.

Using cruise control in the rain

Cruise control is meant to be used on dry, paved roads only. If you should encounter different levels of traction between the left and right drive wheels, the use of cruise control can suddenly turn or spin the car. One minute you’re headed down the highway, trying to see through a wiper-smeared windshield in a torrential rain; with the cruise control on, before you know it you’ve bounced off the median and are now staring into the panicked face of that gasoline-tanker driver behind you. I can’t speak for you, but that’s really not how I intend to check out. Remember that rain on pavement causes oil to rise to the surface, turning ordinary asphalt into the traction equivalent of black ice. When you hit your wipers, turn off your cruise control.

Overdriving your headlights

Years back, I had the opportunity to hot-lap an unlit racetrack at night. It was a completely surreal experience, since none of the senses you rely on to go fast were at normal levels. Beyond about 50 miles per hour, even the high beam lights didn’t provide sufficient illumination to allow for effective vision. I’m not advocating that you drive under 50 miles per hour at night, but I’ll tell you this: on a dark road, at 70 miles per hour, you have about zero chance of missing that deer when he decides to bolt in front of your car. Always adjust your speed to match conditions and your knowledge of the road, and always expect the unexpected.

Pumping your brakes

In the days before ABS, drivers were often told to “pump your brakes” to avoid locking them. While never the best strategy (especially compared to learned techniques like threshold braking), I suppose pumping brakes yielded a better stopping distance than simply locking them. If you learned this, but now drive an ABS-equipped modern car, unlearn it and unlearn it quick. If your car has ABS, and if you have no formal performance driving training, your best bet for stopping in the shortest distance is generally to floor the brake pedal as hard as you can. Don’t worry about breaking anything; in fact, mash that pedal like you were trying to leg-press a stack of iron plates. You’ll feel the ABS system pulse back through the pedal, but that’s normal: maintain as much pressure on the brake pedal as you can until your vehicle has stopped or you’ve driven past the danger.

On modern cars, pumping the brakes will deplete any vacuum assisted brake boost the car has; in other words, pumping the brakes will generally make them weaker. An ABS-equipped car won’t stop shorter than an equivalent model driven by a trained professional, but ABS allows you to steer as you brake. I always encourage drivers to see what their ABS feels like by mashing the brakes at reasonable speed in a snowy parking lot or on a dirt road. The more you understand what a panic stop feels like, the less foreign it will be if you need to hammer your brakes for real.

Riding your clutch

This is another artifact of learning to drive from a non-professional. Ask someone if they rest their left foot on the clutch pedal, and every single manual transmission driver will say “not me”. Why is it, then, that some of us can go over 100k miles with a clutch, while others replace the clutch every 10k to 20k miles? It’s like this: most cars come with a dead pedal for a reason. Your left foot depresses the clutch pedal, smoothly releases it and then goes to rest on the dead pedal until the next shift. Never, under any circumstance, let your left foot ride on the clutch pedal unless you’re quickly working up or down through the gears. Chances are you may not even know you’re doing it, so have someone watch your footwell footwork to see if you’re guilty.

Checking tire pressure hot

In many regards, checking tire pressure is as critical as checking oil, yet most drivers simply ignore both tasks. Incorrect tire pressure can lead to everything from premature tire wear through tire failure, and no one wants to experience a blow out at high speed (been there, done that). Here’s what I recommend: follow your owner’s manual or door sticker as a guide to cold inflation pressure. Front wheel drive cars should carry more tire pressure up front, simply because there’s more weight on the front wheels. Generally speaking, manufacturers are trying to deliver a blend of comfort and performance with their recommended tire pressures; if you don’t mind a slightly harsher ride, it’s usually OK to go a few pounds over their recommendations. Always check tire pressure cold, after the car has sat for at least three hours. Try to avoid checking it if one side has been in sun with the other in shade, as the pressure difference can be as much as three or four pounds between sides (remember that gasses expand as they heat). Always remember to adjust tire pressure for the amount of load you’re carrying, based on the vehicle manufacturer’s recommendations.

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9 Responses

  1. I never knew that you could overdrive your headlights. There are no deers around here, that I know of, but I guess it would be a good idea to slow down more at night. I was never taught any of these things in driving class at all. I was such a bad driver that they never even covered parallel parking with me.

  2. Jean Amaral says:

    Another amazing text.

  3. J D Stadler says:

    Thumbs up. Obviously, many of us were never taught some of these good basics. Praytell, can we get more info about things like threshold braking? Maybe a tutorial series?

    • LWW says:

      I learned more about car control and gained more emergency driving skills in one season of autocross than most people learn their whole lives. Get out to an SCCA event and ask a nice veteran to do a ridealong with you and give you pointers.

  4. 68SportFury says:

    “Pumping your brakes:” I just bought the first ABS-equipped car I’ve ever owned and “Don’t pump the brakes” is at the front of my mind whenever I’m coming to a stop.

    “Riding your clutch”: I sat in the Challenger SRT-392 at the dealer recently and was astonished to see that among the list of warnings wrapped around the left visor. I couldn’t believe people actually had to be told that. My ’91 Daytona still had the original clutch when I took it off the road after 227,000 miles.

  5. 68SportFury says:

    Oh, yeah, the tire pressure thing: I had a guy bitch me out on Moparts a while back because I said I inflate my tires to 35 psi. Higher than the manufacturer’s recommendation? You bet. And I get over 60,000 miles out of a set of tires doing it. And they wear evenly.

    • Kurt Ernst says:

      As a general rule of thumb in a RWD car, I’ll start by setting front and rear at +2 psi from the door label. With an FWD car, I go +3 front and +2 rear. If I’m doing a track day, I’ll use a tire crayon to measure sidewall flex; if it’s more than I like, I’ll add another 2 psi on the tires that are rolling over most.

  6. The_Black_Stig says:

    *Most modern cars have sensors that automatically turn off the Cruise Control if any difference in traction between the wheels is detected.

    Other than that – nice article.

  7. NH says:

    As for overdriving your headlights – there is a good reason why people in rural areas, at least here in Sweden, mounts extra headlights on their cars. 2 big ones like Bosch Big Knick 225 aren’t unusual, but I have seen cars with up to 7 extra headlights.