speedo not working, sat nav instead?

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a pal has broken her shiny saab, speedo is stuck registering 50mph. the quote to fix it is £750
could she use sat nav instead of spending all that cash?
if not, why not?

[db]

that explains the legal side, thanks.
any ideas why a more accurate system isn't legal? no +/- % nonsense

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davepoth said:

In fact the only way I can imagine it happening is if your friend admitted it to a police officer.

ahh, she works as a civilian employee of a scottish police force and has undoubtedly voiced objections to silly money.

the needle is stuck at 50mph so easily noticed when stationary.

thanks for all info regarding gps and it's limits, feeling slightly more educated now