Sat-nav speed

[nicky1]

What's best to believe as being 100% accurate? The road speed displayed on the sat-nav or that shown on the car's speedo?

I have used two different units (and elderly Navman and a new TomTom XL) in two different cars (both cars fairly new) and the car speedo always shows a slightly higher speed than the sat-nav. At 70mph on the sat-nav, the car speedo is around 73/75mph. With so many speed cameras (and I'm not saying they are necessarily a bad thing... until you get caught...) a discrepancy of a few miles an hour could make the difference.

Surely the US military and the GPS system is going to be more accurate compared with a car speedo that's not calibrated?

[Darren]

Sat-Nav is the accurate one, discussed at great length many times before. Rather than re[eat the explanations use the search tool to find the numerous other threads.
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Darren Griffin

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