Bog

I'm considering purchasing a 2009 Audi A4 Cabriolet. Milage seems high at 161K miles.

Any suggestions or tips before purchasing this car? Are there any common problems to be aware of? Any costly maintenance that I can expect coming up? How reliable might a car like this be?

Thanks in advance.

Firefighter

Yes. I also have a 2009 Audi Quattro Cabriolet; please see the photo below.
If you can get a Carfax, please do.
Even with high mileage if the car was serviced by the Audi dealer for its warranted life and thereafter by reputable auto shops, you are probably OK. If you see a service shops that says " Cheap Johns Service" you might think twice.
See if the hydraulic system that operates the convertible top has ever been replaced. If not check to see if the hydraulic pump located in the trunk shows any sign of leakage.
This is a $1,800 to $2,100 part. Check the rear window to see if it is separating anywhere from the surrounding fabric. A replacement top is another $ 2,000 part.
Do not operate the top in cold weather. Yeah, why would you - just to look cool for your friends. Don't do it. The hydraulic fluid is stiffer and the strain on the fabric is especially hard in the cold. Go on You Tube and check out how to raise and lower the top manually if you have to - not a 2 minute operation.
Be sure to use the Audi/VW recommended oil. Castrol 0W-40 in winter and 5W-40 for the rest of the year. This oil is available from Amazon and delivered to your home for far less than your local auto store. Be sure that the battery is checked frequently as a new one is in the $ 150 range.
It is a great car and I hope you love it as much as I love mine.

Bog

Thank you so much for such a detailed response. FYI, Carfax is https://www.carfax.com/VehicleHistor...DF48HX9K006131 and it seems to show mostly Audi/VW dealers.

Curious to know about engine or transmission wear/issues or maintenance that may be due.

I'm looking forward to seeing the car and making an offer this week.

Firefighter

The transmission is sealed and the quattro set up has been around for many years. very reliable in either normal automatic, sport or tiptronic shift mode. You should have no issues with it.
The 2.0T engine is also a long time Audi engine.
The only thing you might check is when the spark plugs were changed last and the four ignition coil wires.
I personally hate to change anything unless something goes wrong. :-)