With room for up to seven occupants, the Audi Q7 is the German brand's largest SUV, measuring 199.3 inches long, 68.5 inches high, and 77.6 inches wide. But not for much longer. Our spies have caught Audi testing what appears to be a prototype of the long-rumored Q9, which will be Audi's answer to the BMW X7 and Mercedes-Benz GLS.

Earlier this year, Audi was spied testing an early Q9 prototype based on a Volkswagen Atlas mule, but this latest prototype appears to have a production body. At the front, the prototype sports Audi's prominent single-frame grille, flanked with slim LED production headlights.

Production taillights are also fitted and it looks like they could extend across the full width of the rear. It looks noticeably longer than the Q7, with an extended wheelbase offering more rear legroom. For reference, the Q7 has a 117.9-inch wheelbase. Reports suggest the Q9 will be 204.7 inches long, making it around five inches longer than the Q7.

Our spies were unable to get a look inside the interior, but we expect the Q9 will borrow tech from the Q8 including its 10.1-inch touchscreen, and be appointed with higher quality materials than the Q7.

As for powertrains, the Q9 is expected to be offered with a plug-in hybrid powertrain and a range of combustion engines. We'll have to wait and see if the Q9 borrows the Q8's turbocharged 3.0-liter V6 that produces 335 hp and 369 lb-ft of torque.

Now that Audi is testing the production version, the Q9 will likely arrive next year, but you won't be able to buy it in the US. Instead, the Q9 will reportedly only be sold in China initially, but we're hoping it will come to the US at a later date to give the BMW X7 and Mercedes GLS some competition.