Using the Vehicle

There may be a time when, as a police officer, you will have to drive fast. Driving fast in a straight line is not much of a problem, but life can get exciting real quick if at high speeds you have to stop or drive through a corner. Studies have shown that while cornering (or making an emergency maneuver), the average driver can use only 40% to 55% of the car's capability. This does not mean they lose control; it means they can no longer put the vehicle where they want to put the vehicle. After 35 years of conducting driver training programs I would say that number is accurate, and maybe optimistic.

Contrary to popular belief, you were not born with the skills to drive fast through a corner. While on patrol you can drive a given corner everyday and think you know it well. Yet take that corner at high speed and it will be like driving around it for the very first time.

Since the "average" driver can use 40% to 55% of the vehicle, what would you experience if you drove a police package Crown Vic through a standard 90 degree corner, one that you find in most urban environments? If you drove through the corner using 100% of the vehicle, your speed through the corner would be 41.5 MPH. Other percentages are listed below.

39.4 MPH
37.2 MPH
34.7 MPH
32.1 MPH
29.3 MPH
26.2 MPH

So the average driver would not make it through the corner at approximately 30 MPH. (Between 50% and 60%)

What can you expect to experience as you drive through a corner at increasing speeds and increasing use of the vehicle's capability? A while back one of the car magazines came up with what happens at the various levels of vehicle usage, and the levels of skill needed and excitement created at these levels. These folks test vehicles for a living, so I agree with them.

If you are driving into a corner using 60% of the vehicle's capability:

It will require constant attention; you can probably carry on a conversation, but you have to be paying attention to the road, and keeping your eyes focused on what's in front of you. Handling characteristics of the vehicle become evident. If the vehicle under- or over-steers, you will start to feel it. If you are average or above average, you can control the forces acting on the car. Driving at 60% is actually fun.

You increased your speed and are using 70% of the vehicle capability:

Your attention needs to be very high. If you are an above average driver, the fun factor has gone up. The fun factor may be increasing for you, but the fun factor is definitely decreasing for your passengers. If people are not belted in, they will start to move around in the vehicle. Objects in the car that are not tied down will also start to move.

80% of the vehicle capability:

This will be a speed at which you cannot afford any superfluous conversation. 80% and above requires complete attention to the driving task. This is difficult, and requires skill that comes from training. If you can accomplish this you are above average. You need to be ready for bad things to happen. Those handling characteristics that became evident at 60% will be slapping you in the face--you will have to use every bit of your skill to maintain control, and the fun factor is decreasing at a rapid rate. Passengers not belted in will start to be tossed around the vehicle, loose objects will become missiles, and the passengers will start to question your sanity.

90% of the vehicle capability:

This will be too fast for anyone but a trained driver with a lot of experience. Small movements of the controls will create loss of control. By this time, "fun" is not the operative word. Even if the passengers are belted in, the force will be so high that they will have a hard time moving their hands and arms. Small amounts of debris or imperfections in the road surface become real hazards. The question the passengers had about your sanity has been answered.

100 % of the vehicle capability:

This would be driving at a speed that allows for no error and no unknown irregularity in the course or conditions. The vehicle will more than likely be sliding sideways. What you were looking at through your windshield will now appear through one of the front door windows. If sanity is intact, apprehension is present. Requires a great deal of skill and some luck; this is reserved for closed-course race car driving, such as qualifying for competition with the pole position in mind.


If you are conducting a training program, you should be pushing drivers to a minimum of 80 %.( my opinion). Also, it is my opinion that if a driver can't use 40% to 45% of the vehicle, they should use walking as a mode of transportation.

Although it is not recommended that you use 100% of the vehicle on purpose, there will come a scenario, maybe not driving through a corner, where you will be required to use all the car has to offer, in a very short period of time and space.

All The Above Can Be Scientifically Measured

There is now equipment available that can be plugged into the vehicle's cigarette lighter and will measure the amount of force the driver is applying to the vehicle. Depending on the level of sophistication of the device, it can be inexpensive ($190) or somewhat expensive ($1200). The device will measure the force (Gs) exerted on the vehicle and how long that force is applied to the vehicle, which in turn tells the instructor how much of the vehicle the driver is using. The high end devices will transmit the results to your computer outside the vehicle. All the results are downloadable.