Why car tracking isn’t a privacy issue

By Felix Salmon
February 18, 2010
said that "there really is something quite creepily Big Brotherish about trying to track every single vehicle in America". But then I heard from Bern Grush of Skymeter, and he's persuaded me that you don't actually need to make tracking information available in order to tax miles travelled.

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Last week, weighing in on a miles-travelled tax, I said that “there really is something quite creepily Big Brotherish about trying to track every single vehicle in America”. But then I heard from Bern Grush of Skymeter, and he’s persuaded me that you don’t actually need to make tracking information available in order to tax miles travelled.

Under his system (and of course he has a system capable of implementing this), anybody who’s pre-paid for their miles will simply see those miles essentially erased from their tracking device as they’re driven — along with the money leaving their pre-paid account. If you pay after you drive the miles, at the gas station, for instance, then the tracking data gets erased then and there.

Of course, you have the option to retain and not erase the data, if you want to keep it for your own records. But if you do that, there’s always a risk that someone could subpoena it.

In a Please Rob Me world, then, where Federal authorities are pushing to be able to track your cellphone, the privacy issues associated with a miles-travelled tax are probably the least of our privacy worries — so long as they’re very clearly articulated, and so long as the default settings are for absolute privacy. If you want to worry about people being able to track your movements, either in real time or in retrospect, then you should probably worry much more about your GPS-enabled phone and your FourSquare checkins than about any tracking device in your car.


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I will gladly trade my privacy for the mayorship of my local (and the Photogenic badge), but you start tracking my car and we’ve arrived in our libertarian nightmare.

I sill don’t understand what makes a miles traveled tax significantly different than a gas tax, plus a gas tax has the advantage of discouraging sitting in traffic.

Posted by bkmacd | Report as abusive

A gas tax has the added advantage of discouraging gas guzzlers.

Posted by vm5 | Report as abusive

Why bother with all the issues around tracking? Why not just increase the gasoline tax at the pump? Not only does this reflect mileage driven, but it gives a discount to those who are more environmentally friendly & using high MPG vehicles.

Sometimes I think we outwit ourselves.

Posted by Lilguy | Report as abusive


The proposal is for a variable miles traveled tax to reduce congestion without using toll booths, etc. So you make the tax really low for driving on underused roads and really high for driving on overused ones. That’s why they want GPS and not just your odometer.

You’re right that a gas tax partially captures that, but most people frankly know almost nothing about fuel economy, so won’t make the connection. If you’ve got a GPS that tells you taking the county roads will cost you $20 a year and the highway will cost you $200 – the cost is right in your face. I don’t think this would kill the gas tax – you want that to encourage high-mileage vehicles.

And yes, the idea does freak me out a bit on privacy grounds.

Posted by AnonymousChef | Report as abusive

God, I just love how over the past 4 years of this big brother road-use metering fear thing 4,231,566 people wrote “this is so stupid, just raise the gas tax!” and three people wrote: “Oh I get it! The electric vehicle can’t pay gas tax, can it? Duhhhh!” Time-distance-place road-use charging is indeed a hugely dumb idea for any country with three things: (1) ONLY internal combustion engines and (2) political leaders with sufficient kahunas to raise the gas tax since 1991 and (3) no congestion. The United States had not had number (2) for the past 19 years (funny, that) and it is threatening to lose number (1), what with all the jabber about EVs. As for number (3), I’ll leave that as an exercise for the reader. Keep fighting for your entitlement to free roads from the transportation fairy, boys and girls.

Posted by BernGrush | Report as abusive

As I wrote at Ryan Avent’s blog:

The biggest problem with the VMT is that it would be impossible to build a real time VMT tracker that was secure. You could still implement a VMT that used annual inspections to check mileage driven, but that sort of VMT won’t get you the infrastructure you need for awesome congestion pricing.

I have not seen any explanation for how we could design a VMT box that is secure. I have degrees in electrical engineering and computer science so I know how to design all sorts of devices, but this is fundamentally very difficult. We’re talking about a device that needs to be attached to the vehicle, and transmit data from anywhere in the country, and has to be secure against user tampering, and has to anonymize user data for their own protection. And it must be cheap. We don’t have good system design principles for solving those kinds of problems, let alone for doing so cheaply. That’s why systems like the xbox or various DRM systems always end up getting hacked. A hacked xbox will save you very little money compared to a hacked VMT counter.

Perhaps I’m mistaken, but it seems like the economists and lawyers have just decided that real time VMT tracking would be awesome, ergo, the engineers can just magic one up instantly. I don’t think that’s true.

Posted by Turbulence | Report as abusive

In general, I think we often confuse anonymity with privacy. You have a right to privacy, you do not have a right to anonymity.

Is it an invasion of privacy if you are seen driving down the street? If someone makes a mental note of this? A physical note of this? An electronic note? An electronic note posted to a friend, a blog, a web page?

Posted by midhenry | Report as abusive


Actually, you do have a right to anonymity in many contexts. Its not as general as the right to privacy, but it attaches to a lot of our lives through the First Amendment. Think NAACP v. Alabama, just for one point.

In any event, what you’re getting at is a question of degree. The collection of isolated data about your life isn’t the problem, its the aggregation of generally harmless data in order to recreate private data that’s the problem.

You don’t go to the grocery store to give off information – you go there because you want groceries and its not easy or cheap to have them delivered. People obviously are under no obligation to forget about it, or to not mention on their blog that they saw Cheffie today and it was great catching up with him. The problem comes when this gets aggregated – when someone starts following me or devouring every blog where my name comes up to put together information about me that would normally be private. There are some legitimate purposes for that (loan qualification or criminal investigation come to mind) but otherwise, that gets really creepy really fast.

Posted by AnonymousChef | Report as abusive

You really believe that law enforcement won’t demand a backdoor for the ability to gather your GPS data? I’m certain that, on cryptological grounds, it’s possible to create a system where your data is anonymous; however I don’t trust any government to implement such a system honestly.

Posted by llimllib | Report as abusive

A short video discussing Skymeter privacy: http://www.itbusiness.ca/it/client/en/ho me/News.asp?id=56420

Posted by BernGrush | Report as abusive

The VMT tax is completely idiotic- an unbelievable amount of complexity and risk for a tiny benefit. The level of anti-rural prejudice it causes is ridiculous. If you are sitting in your car for 30 minutes to drive your Escalade 1 km in Manhattan and I traveled 30km on country road in my Tesla, should I be paying 30x what you are?

Raise the gas tax until we get enough EVs for it to be an issue, create more toll roads and force everyone to get an EZ-Pass equivalent to ride on them.

If EVs really become a serious issue, just start taxing electricity based on the carbon required to produce.

Posted by mattmc | Report as abusive

mattmc: Yessir, put that way, VMT is stupid. But that is the fault of a very poorly chosen name for the time-distance-place charge, which the Europeans (whom we cannot possibly copy for fear of looking like pansies) call it. Reminds me of the Johnny Cash song “A boy named Sue”.

But that is not the intent of the VMT charge (note, I said intent). The intention is that distance is weighted by where, when and what you drive. So your country mile with your Tesla will be way way cheaper than my Manhattan mile in my Escalade.

Raising the gas tax is plain useless (indeed it is stupider still, than the common misunderstanding of the VMT charge). That would be taxing the thing we want you to stop using (gas) in order to pay for the infrastructure we need (roads) to allow you to drive the thing we want you to start using (EVs). How stupid is that?

If you don’t see that imagine we decide to fund the entire US medical system on tobacco taxes (since we’re making lousy progress with any other idea), and then we run out of tobacco? Who’s going to operate on your prostate, then?

Posted by BernGrush | Report as abusive