## Here’s how drivers decide whether to leave a note or ding-and-dash

At what point is a parking lot ding worth a note? That’s the question I pondered last week, when I found lacerations on the passenger door of my minivan. They had not been there before I parked. Now, two hours later, they were as real as real could be – thin scrapes, the kind made when a car brushes up against another – as if someone had taken a wire brush and pulled it across the surface. It didn’t take much detective work to figure out that whoever had been parked beside me had left them, as a kind of anonymous calling card.

I wasn’t surprised. This wasn’t the first time someone had dinged-and-dashed. I wasn’t pleased, but I wasn’t devastated – I was curious. Where was the handwritten note of apology? Legally, when you hit something while driving you are supposed to leave a note. If you’ve caused more than \$1,000 in damage, you must report it to the police. But there is a grey area in which the unobserved individual must make a choice: take responsibility for the error or take off and run.

I believe drivers consider four factors when deliberating about whether to leave a note:

• Potential cost of the repair
• Value of the car damaged
• How I would react if it was my car that had been damaged
• Likelihood of being caught fleeing the scene of an accident

I developed an equation using these factors that calculates the likelihood of a person leaving a note. Here it is:

“Potential cost of repair” plus “value of the car damaged” multiplied by “how I would react if it was my car that had been damaged” divided by “likelihood of being caught fleeing the scene of an accident” equals “whether or not a note is left.”

I’ll use an incident from 2003, when I dinged a car.

“Around \$800 in repairs,” plus “It’s a Porsche 911 parked on Adelaide Street,” times “At best, not thrilled, at worst quite irate,” divided by “There are two young women who saw me bump this Porsche who are obviously praying that I don’t leave a note so they can leave one with their phone numbers on it telling the person who owns this Porsche the licence plate of the guy in a Dodge Spirit who dinged his car and maybe they will fall in love and get married” equals “I left a note.”

Of course, I’m a note leaver by nature. If the damage is bad, it should be reported and, more often than not, if it’s not significant many people will forget about it. I’m also aware that I have a legal obligation.

That’s the theory, but in practice many people elect to ignore this code of conduct. They hit a parked car in the lot, panic, look to see if there were witnesses and, if no one is around, they split. This is the Oxford English Dictionary definition of accruing bad-driving karma. Occasionally, these parking perps get caught because a Good Samaritan who saw the accident leaves a note with their contact information. I once witnessed a driver bash into a parked car and speed away. I called in the plates only to be told the car was likely stolen. I wish there was a website dedicated to chronicling the plights of these no-good creeps being served cold justice. There is not.

With no witnesses, I was left to use my equation to figure out why the person who struck my beloved minivan had dinged and dashed. I entered the variables.

“Around \$200 in repairs,” plus “It’s a 2010 Dodge Grand Caravan so … anywhere from a six-pack of Bud Lite to \$10,500,” times “There are enough smears and scratches on this minivan to rename it the Dodge Grand Pollock,” divided by “I’m pretty sure I’ll get away with this,” equals “No note left.”

Mystery solved.