Lately, I’ve been thinking a lot about the costs and benefits of speeding. Is pushing the pedal a bit actually worth it? Or are you better off staying inside the speed limit?

In order to start cranking the numbers on this, I had to use a few assumptions. Let’s walk through them.

First, I figured that you have 1/4% chance of receiving a speeding ticket for each mile you’re over the speed limit for an hour. So, if you drive 68 in a 65 zone for an hour, you have only a 3/4% chance of receiving a ticket. On the other hand, if you drive 82 in a 65 zone for three hours, you have a 12 3/4% chance of receiving a speeding ticket.

Second, I figured the cost of a speeding ticket is $200 and has a ten minute time cost. The ticket itself will cost you less than that, but the raise in your insurance rates from that ticket will eat the rest.

Third, I figured you lose 1% fuel efficiency for every mile per hour over 65. I’m using government estimates for this figure.

Fourth, I’m using a figure of $2.50 a gallon for gas, and I’ll use a car that get 25 miles per gallon for the calculation.

Got that? Let’s get cracking.

Is it more efficient to drive 80 miles per hour or 65 miles per hour on the interstate? Let’s say you’re making a 200 trip on the interstate.

If you go 65, you have zero chance of receiving the speeding ticket. You’ll consume 8 gallons of gas and arrive in three hours and five minutes, costing you $20.

If you go 80, you have an 11.25% chance of receiving a speeding ticket. If all goes perfectly, you’ll consume 9.4 gallons of gas and arrive in two hours and thirty minutes. However, if you receive a ticket, you’ll arrive in two hours and forty minutes – that’ll happen 11.25% of the time. So, combining the odds of the two, an average trip driving 80 will allow you to arrive in two hours and thirty one minutes (saving thirty four minutes) and cost you $46.03.

So, driving faster saves you thirty four minutes but costs you $26.03 – an hourly rate of $45.11 for driving slower.

What about going 70? You have a 3.75% chance of receiving a speeding ticket. If all goes perfectly, you’ll consume 8.4 gallons of gas and arrive in two hours and fifty one minutes. However, 3.75% of the time, you’ll receive a ticket and arrive in three hours and one minute and drop $200 on that ticket. So, combining the odds of the two, an average trip driving 70 will allow you to arrive in two hours and fifty two minutes (saving thirteen minutes) and costing you $28.55 (costing an average of $8.55 more). Your hourly earnings from driving 65 instead of 70 is $38.91.

What about going 66? Only a completely malicious cop bent on getting their quota would give you a ticket then – you have a 0.75% chance of getting a ticket over three hours. If all goes perfectly, you’ll consume 8.1 gallons of gas and arrive in three hours and two minutes. However, you have a 0.75% chance of getting a ticket, and if you do, you’ll arrive three hours and twelve minutes and get a $200 ticket. Combining the odds, on an average trip going 66, you’ll arrive at three hours and a bit over two minutes (saving a bit under three minutes) and spending $21.70. Your hourly earnings from driving 65 instead of 66 is $36.50.

Here’s the data up through 120 miles per hour. The data in the “TRIP COST” column is the total cost (gas plus odds of a speeding ticket) of an average 200 mile trip on the interstate at that speed in a 25 miles per gallon car. The “SPEED COST” indicates the total cost you incur by going that speed instead of going 65. The “MINS SAVED” column tells you how many minutes you save by going that speed instead of 65. The “HOURLY” column indicates the hourly wage you earn by simply going 65 instead of speeding. So, for example, if you go 120 miles per hour, your trip costs, on average, $126.94, which is $106.94 more than you’d spend if you drove the speed limit. Driving this fast saves you 84.6 minutes on average, though, so if you drove the speed limit instead of going this fast, you’d earn an hourly rate of $75.83 for your time.

Conclusions

First of all, each mile per hour you speed is more costly than the one before it. Going from 70 to 71 is more costly than going from 69 to 70. That’s fairly straightforward, though.

Second, if you look at it in terms of an hourly wage, speeding can be pretty costly. Remember, we’re talking about after-tax dollars here, not the raw amount you bring home. Thus, a $36.50 hourly rate for the two minutes and forty eight seconds you spend driving 65 instead of 66 is more like $50 or $55 an hour in pre-tax money. The chances of a speeding ticket are more costly than you might think.

Third, this doesn’t include a “wear and tear” factor. Continually speeding puts additional wear and tear on your car – an amount that’s hard to quantify. With an enormous pool of real-world data, one could come up with a factor for this, but it would simply serve to make the cost of going faster even higher.

Fourth, this is all about probability. You’ll hear from people who claim to always drive eighty and never get a ticket. Others may get a ticket going 37 in a 35 (the ticket said 42, but I was going substantially slower – an officer was pretty obviously trying to get a quota filled). One lucky person is a great anomaly, but it doesn’t change the simple fact that the faster you go, the more likely you are to get a ticket.

Finally, some people with a high value on their time can justify speeding. If you are hurrying to a place so you can start billing $100 an hour, there might be a great justification in speeding. However, the more you push it, the less you actually gain, because the hourly cost for each mile per hour goes up.

However, on most road trips, you’re better off setting the cruise control at the speed limit and just cruising along. Getting to Aunt Melba’s ten minutes earlier isn’t worth the potential cost for most people.

The comments on this one should be fun. All I suggest is that you shouldn’t get bogged down in picking apart the assumptions, because even radically changing them still results in the same conclusions. I tinkered with and researched the assumptions extensively for this post and found that even if you modify the assumptions radically, the conclusions still hold.