New turbo V6 is way thirstier than the supercharged V6 from the 2019 model.
The old saying "there's no replacement for displacement" doesn't quite ring true anymore. Forced induction has allowed automakers to move to smaller displacement engines without sacrificing power and while making gains in fuel economy. Once displacement has peaked, supercharging is a great way to extract more power from an engine without losing the drivability. Still, the always-on nature of a supercharger doesn't tend to benefit efficiency. That was how the previous-generation Audi Q7 extracted more power from its V6, while the refreshed model switches to the more industry-standard turbocharging technique. However, it appears that the result is poorer fuel economy.
Car and Driver first spotted the weird anomaly of the incoming turbocharged V6 getting worse fuel economy than the outgoing supercharged unit. Both have a displacement figure of 3.0-liters, and while the power bump to the turbocharged engine is an increase of 2 horsepower and 44 lb-ft over the 2019 model, that doesn't quite explain the discrepancy of 2 mpg in the city between the two. The previous model logged in at 19/25/21 mpg city/highway/combined while the new one only manages 17/21/18. That's a sizeable loss in fuel economy and puts it in line with the current Audi Q8.
One possibility is that the 2020 Audi Q7 has gained some extra weight with its additional features, as well as power, over the 2019 Q7, which weighs in between 4,729 and 4,927 lbs. But Audi hasn't given that figure away yet.
For those stretching for an Audi Q7 and want to take better fuel economy over power, there is some good news. Audi has confirmed that a more efficient 2.0-liter turbocharged engine will be available sometime in 2020. Curiously though, the previous 2.0-liter turbocharged engine returnedthe same 19/25/21 mpg city/highway/combined as the supercharged V6. The current V6 version is available now, and starts at $61,975 before delivery charges.