Speedometer off?

Ask technical questions or post on problems/issues related to the Kizashi under this topic. Symptoms and pictures of your problem are a good idea.
NOTE: Any car related technical question can be posted here.
User avatar
LPSISRL
Posts: 991
Joined: Tue Jun 18, 2013 12:49 pm
Location: Chesapeake, Virginia

In a thread about tire size, (viewtopic.php?f=13&t=4476) the question was asked how much it would throw off the speedometer. It was noted that putting 245s seemed to correct the speedometer rather than throw it off. It reminded me that my speedometer seems to be off a bit although I've never checked it at 60 MPH using mile markers. Mine seems to read higher than I'm actually going based on GPS calculated speed using more than one GPS. Seems like about 5%-7%.

So a few questions come to mind...

1. Does your speedometer seem to be a bit off?
2. Does that mean the the odometer is off by the same percentage?
3. If it's reading too high, then would not our warranty be running out sooner than it should? <insert conspiracy theory here>
4. If this is true, what recourse do we have? <insert class action lawsuit details here>
2011 Kizashi SLS CVT (silver)
2005 Honda Odyssey
Priors:
2009 Suzuki SX4 Cross AWD 5-speed Tech package (vapor metallic blue)
User avatar
KuroNekko
Posts: 5170
Joined: Wed Aug 15, 2012 5:08 pm
Location: California, USA

I haven't checked on my Kizashi, but I've noticed in other cars that the speedometer was off by around 2 MPH at around 65 MPH compared to a GPS. One would need a few GPS devices to really figure which one is off, but I think many cars don't have speedometers that are exactly accurate.

I personally don't think it's a big deal. I don't look at my speedometer long enough to care for an exact reading. In fact, nothing with a needle on a gauge in a car is something I rely on for exact readings. I use them to get a sense of where I am whether it's speed, fuel level, coolant temp, or engine RPM. In all honesty, ever since I started driving manuals, I've paid more attention to the tachometer than the speedometer and I don't even do performance driving.

The last thing I want to note is that these readings couldn't possibly always be precisely accurate anyways. Why? It's because the very same set of tires change in measurements as they wear. It's quite obvious that new tires have a slightly larger circumference and diameter than the same type of tires that are old and worn. It's because the treads get shallower as they wear. This is the reason why you should have all four of the same type of tires on an AWD vehicle and not only that, all in the same condition for wear. Hence, if you take into account that tires change in measurements as they wear, you realize speedometers and odometers can never maintain exactly the same (and/or precisely accurate) readings and will have slight deviations from tire wear. This is why I think speedometer and odometer readings were never intended to be precisely accurate.
2011 Suzuki Kizashi Sport GTS 6MT (Black)
WESHOOT2
Posts: 1976
Joined: Tue Jan 11, 2011 5:37 pm
Location: Vermont

I personally agree, and use my speedo only to note how big the ticket --or trip to jail-- will be.......
User avatar
LPSISRL
Posts: 991
Joined: Tue Jun 18, 2013 12:49 pm
Location: Chesapeake, Virginia

I'm thinking more along the lines of a major failure, like a CVT at 95K. A 5% error is the difference between a repair under warranty and having to buy a new car as the CVT repair will typically not be worth it.
2011 Kizashi SLS CVT (silver)
2005 Honda Odyssey
Priors:
2009 Suzuki SX4 Cross AWD 5-speed Tech package (vapor metallic blue)
BLyons
Posts: 226
Joined: Sun May 24, 2015 12:22 am

I thought this had been discussed before, but yes, I believe that the stock tire size reads 2-3 mph higher than actual speeds at 60 mph.
Black 2011 Sport SLS AWD
User avatar
gobster
Posts: 13
Joined: Mon Dec 19, 2016 5:24 am
Location: Perth

The Australian standard for speedometer accuracy says, "The speedo must not indicate a speed less than the vehicle’s true speed or a speed greater than the vehicle’s true speed by an amount more than 10 percent plus 4 km/h."
I'm not sure if the same happens all over the world but I imagine it does.
Odometer accuracy used to have to be +/- 4% but is no longer defined.
I found that using my GPS to track speed (and avoid speeding fines) my speedo usually reads around 110km/h when the GPS says 100km/h.
In my last car (Nissan Navara) I put on bigger wheels and tyres that brought the speedo and the GPS speed in line but threw the odometer readings out (although I never did the calculations to find out how much by)
Obviously there is some sort of magic going on where the speedo can be out by 10% but the odometer is only out by 4% :geek:
User avatar
Woodie
Posts: 1167
Joined: Sun Apr 28, 2013 10:09 am
Location: Laurel, MD

Not only does the tire diameter change from new to worn out, but different tires are not the same diameter when new, even if they have the same numbers written on the sidewall. I think if the engineers get within 5% they pat each other on the back and move on to the next challenge in designing the car.

When I got mine both the speedo and the odo read high (as I have found to usually be the case). With the new, taller tires, they came down a little and one reads a smidgen too high and the other a smidgen too low, can't remember which is which but they were damned close to right.. They're both creeping back up of course, because I've got the tires about half worn out.

My Pontiac Firefly (never sold in the United States) is a real exercise in keeping my brain sharp. The instruments are in kilometers and it has drastically larger wheels/tires on it. Have to apply two different maths to figure out what is going on.
Alcohol, Tobacco, and Firearms
Should be a convenience store, not a government agency
User avatar
Ronzuki
Posts: 2382
Joined: Wed Nov 17, 2010 5:33 pm
Location: Lancaster County, PA

Who's calibrating the speedos? what method is used to determine speed? Who's calibrating whatever GPS device your using to verify/dispute the car's speedo? Standards anyone? No one cares.

The 03-04 Rubicons (can't say about other years) had this exact issue...speedo gear in the tcase was factory incorrect for the 4.10 gearing AND larger tires. It was way off and didn't require GPS to notice how far off it was. You could literally feel you weren't going the 45mph the speedo was telling you were doing. Some one on a forum then did some science to figure out how much off it was and found it was something ridiculous. Daimler-Chrysler knew it, acknowledged it and didn't give a crap. They didn't want to design and fabricate one special. So they threw in whatever gear they already had. Therefore, yes, the warranty, for what ever it was worth on that POS, ran out far quicker than it should have. Wanna fight about? GET A LAWYER. Just remember their bigger than you, have more money and lawyers than you.

Just sayin'...
Ron

2010 Kizashi GTS, CVT, iAWD (3/10 build date)
2011 SX4 Premium Hatch, CVT, iAWD (12/10 build date)
2018 Mazda CX-5 iAWD Touring
2014 Wrangler JKUW (GONE, traded :D :D )
1991 Samurai, 5-Speed, EFI, Soft-Top ( :| sold)
SamirD
Posts: 3074
Joined: Thu Dec 05, 2013 4:07 pm
Location: HSV and SFO
Contact:

It's never really bothered me when the speedo is off because I'm usually driving at a speed that feels comfortable and safe to me. But with our snow set, we're typically travelling about 5-10mph below what the speedo says, the gap increasing with higher speeds.
User avatar
LPSISRL
Posts: 991
Joined: Tue Jun 18, 2013 12:49 pm
Location: Chesapeake, Virginia

What bothers me is that if the speedometer is off, so is the odometer. And the if it's registering too high, the warranty is expiring earlier than it should... by at least 5,000 miles. That's a lot.
2011 Kizashi SLS CVT (silver)
2005 Honda Odyssey
Priors:
2009 Suzuki SX4 Cross AWD 5-speed Tech package (vapor metallic blue)
Post Reply