iPhone Speedometer FTW - 2012 Jeep Wrangler Long-Term Road Test

2012 Jeep Wrangler Long Term Road Test

2012 Jeep Wrangler: iPhone Speedometer FTW

January 05, 2012


Our 2012 Jeep Wrangler now wears big aftermarket tires and wheels, but the diff ratios have not yet been changed. 

Track testing showed that this didn't do terrible things to performance. But while we were at it our VBOX was able to confirm what I'd predicted by comparing tire sizes: the actual speed our Jeep travels at any given time is now 12 percent faster than what the speedometer is telling us.

That's a recipe for a speeding ticket, that is.

At first I considered a conversion chart taped to the dash. And then I found Speedometer+, an iPhone/Android app that uses the phone's GPS capability to produce a speed readout. There's a choice of knots, mph or kph.

I found it in the iTunes store a few days before the new year for free, but that was an introductory offer. They get a whole 99 cents for it now.

Worth it.


It lags a second behind reality, but thats no big deal on account of I usually don't care until I'm at cruising speed. Point is, I know exactly how fast I'm going now.

An indicated 60 mph on the Jeep's speedo is 67 mph as far as the Highway Patrol is concerned. That's a ratio of 1.12-to-1, the same 12 percent error we came up with using the VBox.

Everyone in the office with plans to drive our modded Jeep should get this app. Any smartphone user who has changed their tire and wheel sizes enough to change the height of their car or otherwise suspects a speedometer error should get this app. As an added bonus, the Jeep's dashtop bin contains a small ridge that helps the phone stand up at a useful angle.

OK, Mr. Newcomb, I think this just about takes care of this week's Automotive App of the Week.

You're welcome.

Dan Edmunds, Director of Vehicle Testing @ 7,074 miles

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