I have the reverse problem, I’m used to MPH and in the process of getting more familiar with KPH. However, I actually find it very useful to have two different readouts of my speed, one in MPH for the HUD and the cockpit display showing KPH. This lets me slowly learn what KPH speeds correspond with my more familiar MPH.
From a realism perspective, I can see that cars with the ability IRL to toggle MPH/KPH on the digital speedo should respect the UI settings, but realistically this would also likely depend on where the car was sold and what dash unit was put in.
I’m not sure why you’re seeing this issue with BMW and Lamborghini, in my game with the HUD set to MPH the digital speedos show speeds in KPH for these cars. Usually I only see MPH on actual American cars.
The in-car dash will use whatever units were on the real car that Turn 10 scanned. Since they are an American company, the majority of the “world” cars in the game would have been LHD American-delivered models and thus use MPH. For cars that were not available in the US (such as RHD JDM or Australian cars) they would use the relevant units from those countries (km/h), however these are much less common in-game (although a bunch of them would also have been LHD from Europe, but most of continental Europe uses km/h)
I think we should have an option to have MPH or KMH in cars that actually come that way to the States or over seas.
Don’t known if I’m the only one but I wish that the cars with an Actual HUD inside actually displayed it like Gran Turismo 5+ yrs ago.