Tesla driver’s speeding ticket pits on-board data against Calgary police officer estimate

McKay said estimate speeding tickets shouldn't be a thing anymore

Calgarian Scott McKay got a hefty speeding ticket, but data from his Tesla tells a different story. CONTRIBUTED

When Scott McKay got hit with a $373 speeding ticket while driving his Tesla Model 3 in southeast Calgary late last month, you can imagine what he said.

But, the data McKay pulled from the vehicle’s computer tells a different story than that of going 120 km/h in an 80 km/h zone.  It’s raised an interesting legal test in his mind when it comes to reasonable doubt in court.

McKay had just visited a client and wanted to hit the Home Depot west of the intersection of Glenmore and Deerfoot Trails.

When he left the Home Depot, McKay went eastbound on Glenmore Trail to hit Deerfoot Trail southbound. When he merged from the overpass on to Glenmore Trail just before Blackfoot Trail, he saw the red and blues of a Calgary police cruiser.

“I haven’t been pulled over in a long time, so it kind of makes me a little bit nervous. I’m not a perpetual speeder or violator, or any of that kind of stuff,” McKay said.

The officer walked up to the window, according to McKay, and asked him if he knew why he’d been pulled over.

“He said, ‘I estimated you doing 120 in an 80 zone… license, registration, insurance,” McKay said.

“It didn’t sit right with me. Even with he handed me the ticket it didn’t sit right.”

McKay said he’s been driving a while and figured he had a good idea of his own estimated speed. He admits he probably sped up to merge into traffic, but wasn’t convinced it was 120.

“Then I remembered I subscribed to this software called TeslaFi,” McKay said.

‘Data centre on wheels’

Most new vehicles today feel like they have more microchips than a typical laptop computer.  Especially a Tesla, McKay said.  

“It’s basically a data centre on wheels,” he said.

McKay figured he’d see if the data available on the vehicle matched the ticket he was issued showing he’d exceeded the speed limit by 40 km/h.

TeslaFi is an Application-program-interface (API)-driven data app that shows Tesla owners the diagnostic information on their vehicles at a given point in time.

McKay pulled the data for the time in question. It showed that his vehicle didn’t exceed 97 kilometres an hour.  His average speed from 1:06 to 1:09 p.m. that day was 31 kilometres per hour.

Data from McKay’s TeslaFi account. CONTRIBUTED

When asked, the Calgary police said they couldn’t comment on the specific situation because it was to go before the courts.

They said vehicle data isn’t court certified, meaning that it hasn’t yet been adequately tested as evidence in a court of law in cases like this.

GPS data, in particular, isn’t always 100 per cent reliable in based on available satellites and the specific point in time data. This data is often used in collision reconstruction, but only has one piece of the puzzle.

When we asked TeslaFi if their data was court certified, they confirmed it wasn’t.

API script from the TeslaFi account. CONTRIBUTED

They directed us to a website on the data, which comes from Tesla’s “unofficial API.”

There it said: “Gives point-in-time data about the state of the vehicle and basic controls over certain functions of the vehicle.”

It said it streams the data at half second increments.

Police estimate tickets

McKay said the one aspect of this that concerns him more is that he’s taking it on the chin for an estimated ticket. If he’d been clocked going that speed, it would be an easier pill to swallow.

Sgt. John Hebert with the Calgary Police Traffic Section said most people – like officers – already do speed estimates on a regular basis. They’re testing how quickly a vehicle is travelling at an intersection or when a vehicle is travelling towards them.

Calgary police use that instinct and they train to become more exact.

“Everybody who gets introduced to speed enforcement gets taken out to a couple of different locations and they actually fill out a sheet and do start doing estimates,” he said.

They track the actual speeds versus the estimates.

“We work on developing that, getting it down to more of a finite number,” Sgt. Hebert said.

What they’ll quite often do is estimate the speed of a vehicle in a fixed location before activating the speed detection device. That way they can confirm the estimate.

In cases where there isn’t a fixed location and a police cruiser is following, Sgt. Hebert said the officer looks at the totality of the situation. They may have to speed up to reach a vehicle, or that vehicle may be pulling away.

There are other giveaways when vehicles are speeding up or slowing down. It could be the obvious brake lights, or a lowering of the vehicle’s nose that indicates reduced speed, said Sgt. Hebert.  They also train estimating speeds against other moving backgrounds.

He likened it to a baseball batter learning to judge the speed and direction of a pitch.

“That baseball player uses that experience and knowledge about how that looks to decide whether or not to swing.”

Beyond a reasonable doubt

McKay said he’s going to fight the ticket.  He believes the evidence from his vehicle provides enough reasonable doubt to have it quashed in court.

“The Crown has to prove I was doing 120 so I don’t know how he’s going to be able to do that,” he said.

It’s worth it, McKay said. The ticket comes with four demerits and likely a big bump to insurance.

He’s also concerned about the number of estimated tickets that are being doled out to drivers without this kind of onboard analytics.

McKay said it’s a case where maybe traffic enforcement hasn’t caught up with the technology available in vehicles today.

“Is that tailing me enough? Did you follow me enough before you lit up the lights and pulled me over to the side? My data says no. I don’t know what the judge will say,” McKay said.

About Darren Krause 1185 Articles
Journalist, husband, father, golfer, writer, painter, video gamer, gardener, amateur botanist, dreamer, realist... never in that order.


  1. The time has long passed when the word of a police officer can be taken as reliable. EVERY testimony should be backed by video evidence.
    Also, this driver is going to lose. It’s a rigged system and it takes a very specific set of skills to navigate the “judicial” system effectively due to the massive amount of corruption that’s ingrained in it.

    • How is this driver “going to lose”? I’ve won every ticket I’ve disputed in court, where the officer was using “judgement and experience” instead of calibrated measurement equipment.

  2. It’s awful that the police do this. It has to stop. So glad this man had a Tesla and could dispute this. There are millions of people out there who have no way of contesting this and they have to pay these ridiculous fines!

  3. Our human minds play tricks on us all the time. Honest mistakes happen when we do estimations, and I can see how one can mix speed with acceleration, specially on a Tesla. It is also very easy to make a repeatability (GRR) study on the Tesla system, and a correlation study with another instrument. Even customers can do that by comparing with their speedometer, but start with constant speed.

  4. Police are trained and tested in the estimation of speed. It is an important component of tracking history and serves well to support other equipment or methods used. Most officers will testify their estimates are +/- 5-10 kph depending on conditions, and adjust alleged speed accordingly. I’m guessing the crown will amend the charge to “disobey traffic control device” (the 80 sign). They both seem to agree on that).

  5. Had a similar incident many years ago in Idaho! Trooper estimated my speed. Judge threw it out

  6. the reason it will never go to court is because the courts have ruled that that 0 tolerance is the law based on facts, allowing estimates to be challenged would seriously reduce the income they gain. this is also the reason that you can usually have tickets reduced ahead of time for it is far more expensive and time consuming to allow it to go to court. The shear number of tickets written per day for the purposes of bumping up the coffers would bring their taxation system to an absolute standstill. if everyone asked for a court date for a ticket they would be booking out past a year with in the first weeks and adding a year to the schedule every week thereafter.

  7. You have the opportunity to challenge all traffic citations because they have court dates attached to them. The system relies on the fact that the vast majority of the people do not challenge them and simply pay.
    Reducing successfully challenging estimated tickets is largely based on the opinion of the driver about their speed. In this instance, this is hard data so the question is really whether the opinion of the policeman estimating the speed is more valid than the hard data coming from a computer system.

  8. Radar guns aren’t reliable in heavier traffic areas. Hence the need to “estimate” which is wildly inaccurate. And as for the Tesla data not being court tested? At least it’s measured and recorded by calibrated equipment. When was the officer’s “ability” to guess speeds calibrated?

3 Trackbacks / Pingbacks

  1. Tesla Owner Fights Speeding Ticket with Vehicle Data from TeslaFi - TeslaNorth.com
  2. Tesla driver's speeding ticket pits on-board data against Calgary police officer estimate - Tesla News
  3. LWC's Top 12 most-read stories of 2021 - LiveWire Calgary

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