Smartphones are the new speedometers: an experiment

speedometer smartphone
Screenshot taken from the author's smartphone en route.

In which our editor in chief drives around the US testing Google Driving’s new speedometer feature and generally saving a lot of money in the process. Result!

Earlier this year, I wrote about my experience with a rental car that came with a GPS navigation unit, which turned out to be a cheap smartphone with a dedicated navigation app. At the time, I pondered whether I could save the extra cost of a GPS rental fee by simply using my own smartphone and the Google Driving app.

Well, I’ve been in the US for the past week doing just that.

And I have to say, I’m impressed.

Preparing for the trip meant investing in a dashboard mounting rig and a USB power adapter for cars – which are easy and cheap to buy in Hong Kong’s Sham Shui Po district, as taxi drivers use them all the time. Once I acquired the car in O’Hare, it took under a minute to set everything up on the dashboard. I opened the Driving app, input my hotel address, and off I went.

It worked like a charm.

I’ve driven from Chicago to East Tennessee and back again, and if this week’s experience is anything to go by, Google Driving does pretty much what it’s supposed to do – it knows where you are, how you need to get to where you’re going, and what time you will arrive with uncanny accuracy. It knows how to reroute you efficiently if you make a wrong turn. It even knows where the traffic jams are, and by how many minutes it will slow you down.

You can use it to avoid toll roads and report speed traps. It also knows what the speed limit is where you happen to be driving (provided you’re driving on a major thoroughfare or freeway). Not only that, it even knows when you’re exceeding that speed limit.


Google rolled out a speedometer feature in June to Android phone users. It shows up next to the speed limit icon (or by itself if the app doesn’t know the speed limit where you happen to be driving), and displays your speed in real time. It also turns red when you go above the speed limit.

I’ve no idea how it works, but I can tell you it’s jolly accurate – the app’s speedometer matched the dashboard speedometer perfectly.

Which of course raises a valid question – why would you add a speedometer to a navigation app when there’s a perfectly good one already built into the car?

According to Cnet, one reason is that if your smartphone becomes a central feature of the car’s dashboard, it’s safer to have other info like speed on the same screen rather than looking back and forth. On the other hand, I already have to do that for things Google Driving doesn’t support, like petrol levels or the radio. (Yes, I know I can connect my phone to the car via Bluetooth and stream music, except that after half a dozen rental cars in as many years, I have never successfully been able to pair my smartphone with a car. Not once.)

That said, I can see it being a useful feature for people with older cars whose speedometers have stopped working. So it could save you money in repairs, if nothing else.

One other thing: I’m using a prepaid SIM with an 8GB data plan, which I mention because in my earlier article, I wondered how much data Google Driving would eat up.

Not much, as it happens. In the seven days I’ve been using it, I’ve only burned up 140MB – which is negligible when you have an 8GB limit.

So all up, it’s a useful app that saves me a considerable amount of money, and all it cost me was the price of a dashboard mount and a charger – and my privacy, of course, but as we say back in East Tennessee, “that horse done left the barn.”

1 Comment

  1. OK, it’s time to stop playing around with your new-found tech toys and get back to work! Presuming, of course, you can get back into Hong Kong easier than it was for me to get out!

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