In the US, their sales grew from 7.8 percent in 2017, selling 226,511 cars. That trend continued during December, where the car manufacturer managed to sell around 26,977 vehicles to close the year. Those sales saw Audi create a 16.3 percent profit, which continued its rise year after year.

Business Wire reveals that the results were fueled by the strong performance of the Q5 and Q7 SUV models. The A5 line was also instrumental in the last quarter push; it also helped that, in the US, the A5 Sportback created a new market, boosting Audi sales in that market.

Now it's China's turn as Mercedes-Benz is bested by the German automaker for the first time in the country. Audi China posted car sales that rose by 3.8 percent, good for 53,191 units sold. In contrast, Autonews Europe reports that Mercedes-Benz posted at least 8.3 percent of sales, good for 52,616 units sold; a lot lower than those of their fellow German automaker.

While the focus of Audi on the American market isn't lost, China is where things are happening currently. The A4 sedan did it for Audi; the deliveries of these vehicles hiked all the way up to 33 percent in 2017, mimicking how the US market embraced Audi products. In China, while Audi trailed Mercedes consistently for seven straight months, they eventually overtook the lead this month.

In those first seven months, Audi's registrations were worth 17 percent for about 359,781 units sold. Mercedes posted 15 percent or about 392,780 units registered during those months. BMW, for its part, stood pat with 4 percent, or about 330,671 units registered.

The ongoing dispute China has with the US may affect the markets, but China has lowered the tariffs it earlier imposed on imported vehicles. This helped the case of Audi, which does not import its products from anywhere in China. In contrast, however, Mercedes and BMW have been exporters. Mercedes makes its GLE and GLS models in Alabama, while BMW X5 and X6 model ship in from an assembly plant in South Carolina.

What works for Audi isn't working for Mercedes and BMW, which may see themselves continually trailing in sales as long as the US and China remains at odds with each other.