I have been driving on the Continent, in China and certainly in the UK. I have also driven once in the States. Some countries use miles and other use kilometres. The only common thing that I found on all the roads that I have driven is that the distance from a sign post to your destination is often shown. Such distance notices are shown every so often on the road.
For a given distance, the number of the measured distance in kilometres is greater than the number of the measured distance in miles.
If you are driving from City A to City B and seeing those distance sign posts every so often, then I am sure you will certainly be watching the numerical values printed on the sign posts just to keep track on the distance from City B. I think you will certainly not worry too much about whether the numerical values are miles or kilometres. I am sure you will most likely checking its absoulte value rather than converting to the usual unit that you are familiar. You will find that the numero-dropping of kilometres per unit time is much faster than the numero-dropping of miles per unit time. In terms of the psychological effect:
one feels that the approaching to City B is faster because the decrease in the numerical value per unit time is higher when the sign posts show the distances in kilometres.