DigiHUD Pro, at a stable speed is very steady.
You can even option it to display 0.1 km/h increments below 100 km/h.
Night time display
Day time display
Another day time display you can use.
Another option with the display in both landscape and portrait.
How I use it in split screen.
You can set speed limits in it and the numbers are that colour, up to that speed. e.g in the photo below it's yellow from 81 to 100. You can even choose your colours.
You can even have audible overspeed warnings and choose between off, single and continuous.
It also logs statistics like max and average speed, all-time max, (I used it on a jet and got 975.78
)
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