XK speedo bonkers

[Simpo Two]

When I brought the car home a week ago the cruise control showed 72mph but the speedo read 79mph - that's +9.7%.

A few days later both the cruise control and speedo read the same. I thought/hoped the car had magically recalibrated itself.

However today the cruise control showed 29mph but the speedo read 44mph - that's +51%!

Judging from the other traffic, the cruise readout is accurate and the speedo is bonkers. When there are speed cameras around I need a speedo I can trust.

Does anyone know what's happening? I'd like to get the facts before reporting it to the dealer in case they try to fob me off with BS.


ETA: Now that's imperssive, I put 'jaguar xk speedo accuracy' in Google and my own post came fourth (after XF hits). If I use 'jaguar xk speedo accuracy -XF -XE' it comes top! Evidently every other XK speedo is perfect...?

Edited by Simpo Two on Friday 23 June 20:50

[Triple7]

Hmmmm, is the digital speed same as the needle on the dial? Mine is spot on.....

[Simpo Two]

Triple7 said:

Hmmmm, is the digital speed same as the needle on the dial? Mine is spot on.....

Nope, that was the problem.

Last week when a 30mph speed camera came up I slowed down until the speedo read 30, and I'm sure the car can't have been going at more than 20mph.

Yet today it was perfect, or maybe 2mph over.

Weird.

[w824gb3]

Needle speed and digital speed shown on cruise should be identical. Both will be showing slightly faster than true speed which you can check with any number of free smartphone apps.

[Simpo Two]

Since starting this thread the speedo has settled down and now almost exactly matches the cruise display.

Wonder why it said 44mph when I was doing 29mph?

The wonderful irony of the XK I'm discovering is that whilst it makes no practical sense whatsoever, it fits the bill perfectly