What is the root cause of poor fuel efficiency in Audi A6?

I've been noticing that my Audi A6 is not getting the same fuel efficiency as it used to. What could be the underlying issue causing this?

One potential reason for poor fuel efficiency in your Audi A6 could be a clogged air filter. If this is the case, it's important to replace the air filter as soon as possible to improve your car's fuel economy.

Another possibility could be a faulty oxygen sensor. This component measures the exhaust gases and determines how much fuel your car needs. If it's not working properly, it can lead to decreased fuel efficiency.

It's also important to make sure your tires are properly inflated. Underinflated tires can increase fuel consumption by up to 3%. Regularly check and adjust your tire pressure to improve fuel efficiency.