What is more accurate, my sat nav or my cars speedometer?
Joe N asked:
Recently got a sat nav, and noticed that when my cars speedometer is reading 70mph, the speed shown on my sat nav is 65mph. So which one is accurate?
Mobile phones insurance
Recently got a sat nav, and noticed that when my cars speedometer is reading 70mph, the speed shown on my sat nav is 65mph. So which one is accurate?
Mobile phones insurance
Sat nav I think.
sat nav is more accurate, they say that a cars speedo is 10% air, which means your actually doing 10% less than your cars speedo.
I would say speedo.
there might be a slight delay on your sat nav.
Your spped will be even more accurate if you have an electric speedo in your car
If your car has an old fashioned cable speedo then the sat nav but if car has digital then if the tyres are correct the cars will be the more accurate. Maybe.
The GPS is actually more accurate than the car’s speedometer. Some auto manufacturers are not all that worried about accuracy.
I don’t know in your case but in mine I proved the sat nav VERY wrong: it said it was 60 miles to get there when everyone and his dog knows it’s 90 miles unless you get there by plane or something.
It is the sat nav, as your speedo has by law to read 10% higher than your actual speed.
I noticed the same on my tom tom, you will notice that 10% is about right, ie 100 = 90mph, 30= 27mph 70=63mph
Many possible variables here - make/age of your car; whether your tires are original-sized or excessively worn; make/model of GPS; whether GPS has WAAS enabled, etc. Aviation GPS with WAAS are dead-on accurate, not so sure about automobile types. Generally speaking, if the car is more than a year or two old, the GPS is probably better for determining average speed on a given stretch of road.
The sat nav is more accurate - car manufacturers always make the speedometer read more than the actual speed so drivers can’t say it was the speedometer showing a low speed that misled them
By law your speedo can show your speed at up to 10% more than your actual speed i.e. if your speedo shows your speed as 30mph you might only be doing 27mph and if it’s showing 70mph you might be doing 63mph. And I think speed cameras take this into consideration, but I’m not 100% sure. I use a satnav every day but I wouldn’t rely on whatever speed it tells me I’m doing. Stick to the old-fashioned way of relying on your speedometer.
SAT NAV every Time.
It tracks your position using 3 satellite’s so it knows exactly where you are down to approximately 6 metres.
Your car speedo has a plus or minus tolerance of typically 10% so at 70 you could be doing any thing from 63 to 77 mph. Simlarly over say 100,000 miles you could have paid for more services than you actually needed!
My new vehicle speedo was 12% out so i took it back and they fitted a new one. This is 16% out!!
So there you have it.