Not sure, but this is not what you asked for which is available now in 2.1?I am completely fine with speedos in the cars, I never use the inside view anyway - I mean the bar in the lower left corner:
And many EU cars have the ability to change what is displayed electronically from km to mi since we have our friends from the UK as well .
Being able to change the unit of the HUD Speedometer?
I have not fully read this thread, but there is also this setting some of players might not know.