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What U.S. cities have the most aggressive drivers?

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As the last holiday weekend of summer approaches, many of us will take to the roads for one more car trip. And encounter a couple of tailgaters, or drivers who whizz by and then cut us off.

In all likelihood we’ll do an informal survey based on our own experience and say something like: “This state (or city) has the nastiest, most aggressive drivers I’ve ever seen!” Or we may focus on the vehicle that’s been riding our bumper, be it an over-sized sport utility or a flashy foreign number with a license plate that reads “FASTER,” and make the same sort of generalization.

We’ve probably all done this, but honestly - what’s the truth? Automatic, a San Francisco-based company that sells an adapter – also known as a “dongle” – which attaches to a car’s OBD (on board diagnostic port) found under the wheel, provides one answer.

Its answer: Phoenix, Arizona, is the most aggressive city for drivers. And a Porsche -- no surprise there -- is the choice of the most aggressive of drivers (see map below).

Fatal highways: America's 9 most dangerous places for drivers
Fatal highways: America's 9 most dangerous places for drivers

Like the dongles used by insurers such as Progressive and State Farm, Automatic’s adapter measures, among other things, acceleration and braking. Both rocket acceleration and stomp-on-the-pedal braking indicate aggressive driving.

Automatic provides this “acceleration profile” to auto insurers Liberty Mutual and USAA, the company said, and in addition provides feedback and other services directly to motorists who often purchase the device for themselves online and then receive their driving profile through their cell phones or online.

According to company cofounder Jerry Jariyasunant, Automatic has come up with a profile of the most aggressive drivers by city, state and type of vehicle as a result of analyzing “billions” of miles of driver behavior since 2013.

Some of this fits in with what we’d expect. Wisecracks about BMW drivers are common, and here’s no disputing those Los Angeles freeway drivers.

But just because you drive a Porsche in Phoenix, don’t feel you have to cut people off. Remember that every study has its parameters, and its limitations.

Unlike some insurers, Automatic computed all the times that drivers accelerated and braked and put them into groups ranging from (1) going to and from zero miles per hour, (2) city driving at 20 to 45 mph and (3) highway driving (45 to 75 mph). This way it was able to control for drivers who spent more time on highways versus taxi drivers, for example.


The profile also ruled out speed as a factor. It didn’t take into account how fast the driver was going or what was the speed limit. Another limitation: Automatic used a statistically significant sample from only 44 states, and pre-selected 73 metropolitan areas to analyze because of their location and population.

Vehicles were grouped into buckets, so that the Hummer you saw bearing down on you was only one of a large number of sport utility vehicles, many of which are actually driven very safely.

So why do people drive the way they do? Automatic doesn’t have the answer, but Jariyasunant has some thoughts on the matter.


He said that certain cities tend to lend themselves to certain cars. Cities with large numbers of minivans have less aggressive vehicles, perhaps because they tend to transport children.

He considers a city’s design to be another factor. Urban sprawl with multiple lanes of superhighways, like Los Angeles, lends itself to more aggression as drivers see themselves as being on a racetrack.

Then he points to the amount of traffic. Congestion doesn’t necessarily slow people down, but can instead make them go faster to escape the crowd.

Now let’s see where you fit in.

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