mcat

Got a Nuvi 1300 for Christmas and have noticed my speedo is about 2-3 mph higher than my Garmin.
Which do I believe? Why would this be?

I have a 99 Ls.

Also. looking to get a vent mount. Any suggestions?

Thanks,

cat

PureDrifter

iTrader: (10)

afik that's fine, your speed is +/-5% error i believe, due to tire size/wear and meter calibration.

Twix

By car manufacturing law speedo in every cluster of all cars (Lexus, Merc, BMW....you name it) must show higher value than actual...

I never knew this until a friend that works in Mercedes-Benz in Germany told me this...

PureDrifter

iTrader: (10)

there's no NHTSA or DOT law defining the required accuracy of speedometers. the SAE has various standards which are all voluntary. some manufacturer's do read a little low, some high, all are generally within 5%-10% accuracy.

edtbjon

In my experience most cars shows some 5% more than the actual speed. I don't think it's a "law" but for sure it's common practice and any manufacturer would have big problems if anyone could claim that their speedos were calibrated to show too little.
I'm currently a truck driver and most trucks here in Sweden have calibrated speedos, i.e. they show how fast I actually travel (also compared with a GPS). I've noticed that I very often "get stuck" behind someone who believes they are driving at e.g. "exactly" 70 km/h, while they are doing 65-67. Also here in Sweden we have warning signs saying that there are speed trap cameras further down the road, which can be a terror when wanting to maintain a constant speed. Many drivers do slow down some extra 10-15 km/h whenever they see the camera (or even well below 70 on a 90km road, just to make sure), causing everyone behind to have to slow down too. The worst scenario is when coming up behind one of these drivers with a fully loaded truck and trailer hoping to maintain most possible speed for that long uphill in front of me and the "sucker" breaks just at the start of the hill. No problem if in my Lexus, but big problem in my truck as I know that I will have to go through almost every gear in the gearbox to make it to the top. The driver in front of me is by then long gone (at least until the next big hill...) and I've run out of fingers to show him.

//Björn

Mikenbon

I was going through a construction zone last week and a radar system was set up displaying my speed. I noticed a 4 mph difference! It doesn't matter to me though because this car is so nice to drive I've slowed down just to enjoy it more.

Twix

Well this is what the guy from Merc tells me , if he lies - I lie, therefore I'm sorry

I tested quite a few cars with my GPS (I own 3 cars, and it's all the same), they all showed faster speed than actual...

mcat

My motorcycles are optimistic, too. My Triumph is about 10% over and my Goldwing about 5%.
The LS seems reads about 5%.

cat

Kansas

Yes, the speedometer in my 2000 LS400 is also 2-3 mph slow at 70 mph -- pretty typical.

I'm not a fan of vent mounts. This thread has information on how I mounted a portable GPS in my 00 LS: https://www.clublexus.com/forums/ls4...tion-help.html

mkaye

my 96 actually reads ~2% low compared to the GPS - i would rather have it the other way, so i am careful
remember that a GPS shows velocity, while the speedo shows speed, so make sure you're on a flat road when comparing

mark

tromly

^^^1, that's my reasoning for driving my SC430 so slow