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SAFE DRIVING TIPS
Putting the brakes on panic stops
We crunch the numbers and the results might surprise you
By Richard Russell
Thursday, November 20, 2003
After conducting instrumented testing recently at the annual Automotive Journalists Association of Canada's (AJAC) TestFest activities, it became clear once again that the differences between vehicles have a direct impact on crashes. During training we have to use a lot of generalization, but in the real world there is a huge performance gap between vehicles, particularly when it comes to panic stops. Three of us were responsible for conducting controlled tests of all 58 entries at this year's event. Using carefully calibrated digital equipment we measured acceleration (zero to 100 km/h), passing (80 to 120 km/h) and emergency stopping (100 km/h to rest). Testing was conducted on the same surface, on the same day with each of us responsible for all vehicles within a class to ensure uniformity. Tests were repeated as necessary until the numbers were consistent. These were all brand-new vehicles on properly inflated tires. Brakes were bedded in and everything at proper operating temperatures. In other words - optimum conditions. Braking distances were measured in feet because the greater number of units allowed better comparison (i.e. 150 ft. compared to 45 metres).
Let's look at three distinct areas and how they reflect on everyday driving and traffic safety. Acceleration from rest is arguably the least significant but the numbers give an indication of ability to merge from very slow speeds or rest. No surprise here - a 500 horsepower sports car led the pack at 4.7 seconds, while the slowest was a soon-to-be-released 4-cylinder pickup truck at 16 seconds.
The gap will be even worse when the pickup is loaded.
Acceleration from 80 to 120 km/h is indicative of passing ability and the amount of time exposed to oncoming traffic on rural roads. A $175,000 luxury sports car recorded the fastest time of 3.7 seconds. The slowest was a new utility van at 15.2 seconds - a huge gap and destined to be even more so when the van is loaded.
Arguably the most important statistics were those of emergency braking distances. The gap between different vehicles and types of vehicles was huge - 61 feet or four car lengths between the best and worst vehicles.
SUVs get a lot of criticism, but pickups are the problem. In fact, the shortest stopping distances we recorded belonged to a new crossover/SUV-type vehicle, while the worst was a pickup. In our measured tests, pickups required an average of 163 feet to bring to a complete halt from 100 km/h. Several other categories averaged 30 feet less.
To put that 61-foot span stopping distance into perspective, consider this: If the pickup truck was following the crossover and both drivers stood on the brakes at precisely the same moment in time, the pickup would have to be four car lengths back to prevent running into the lead vehicle.
In the real world, the driver of the pickup truck would not even go for the brake until seeing brake lights ahead. This would be followed by reaction time and the time to physically get to the brake pedal, typically anywhere from three-quarters to two seconds - 75 to 200 feet or 5 to 12 car lengths. Add that to the four-length difference in stopping distance and you can see that under normal conditions the pickup would have to be at least nine lengths behind. Does that ever happen?
The average braking distance of new sport coupes and sedans wearing price tags under $35,000 is 142 feet and the spread between the best and worst is 39 feet. For economy cars the average is 145 feet and the spread 20 feet. Minivans require an average of 137 feet to bring to a halt, with 14 feet between the best and worst of the new ones. The new brand of MPV/crossover vehicles averaged 131 feet with 16 feet between best and worst. SUVs averaged 136 feet with a 20-foot spread. Family cars average 139 feet with a 16 foot spread.
The best of the lot were not sports cars, but sport coupes and sedans over $35,000. With their massive brakes and high-end performance tires, they average 120 feet with only 7.5 feet between best and worst. High-end sports performance cars weren't far behind at 123.5 feet, but there was a 16-foot spread in the class.
The big numbers were posted by the pickups. The category this year included a number of full and mid-sized newcomers from both domestic and import manufacturers. Here we measured stopping distances averaging 163 feet, with the worst offender requiring 175 feet and the very best 150 feet.
When you consider your next vehicle - or look in the rearview mirror - think of those numbers.
Halifax-based Richard Russell operates the Advanced Driving Concepts driving school.
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