It's unfortunate that the only written mechanism we have for expressing a lack of precision is scientific notation, which tends to be obfuscating for numbers at this scale: if you write "3.6e3 kph (2.2e3 mph)", you make it clear approximately how much precision you do and don't have, but it's less obvious-at-a-glance for the target audience of an article like this.

Or use kps and not lose additional precision every time you translate units?

2200 would improperly add an extra significant figure, "about 2000" would be okay.