Why are MPG(US) and 100km/liter ratings do not match?

The question here is, why on earth for the same exact car in one country, the 100 km/litre consumption rates do not match with the MPG ratings in another country? 

Ex; BMW 328i is supposed to consume 8.1 litres/100 km in city, 5.2 litres/100 km in Highway according to the BMW's Turkish website.

Now, these numbers converts into 29 MPG(US) in city and 45 MPG(US), if you google "xxx l/100km in mpg". 

The problem is, the number in BMW's USA website is 23/35 MPG respectively for the same car. 

Another example is Nissan Juke Nismo. The Turkish website claims a consumption rating of  9.1 and 5.6 l/100km, which converts into 26/42 MPG (US). US website on the other hand claims 25/31 MPG(USA). 

For Prius C in US website the consumption is claimed to be 53/46 (city/highway) MPG(US)  whereas in Turkish website it is 3.4/3.7 l/100 km which converts to 70/64 MPG(US).

The rating for US and European cars are different so the ratio of MPG(US) to conversion from Turkish websites should be constant right? or i guessed so...?

The following chart summarizes the above, and the it will be extended in the future for more cars...Now here is a spreadsheet including the websites attached on the consumption values;

Feel free to comment below...