I am from Austria so if you have any questions just DM me or ask them here.

What comes to my mind is all the beautiful lakes we have (Faaker See, Wörthersee, Weissensee, etc) so be sure to make a stop at one and go for a swim.

Our capital Vienna is also really worth it but I fear that there is simply too much to see/do there that it alone could fill a whole week.

If you want to see how your car handles mountain roads you can also visit the Großglockner which is the highest mountain in Austria. You can also go for a hike there if that's something you like.

Salzburg is also really nice and pretty for a day trip.

I even visited Hallstatt a few weeks ago but I sadly have to admit that although it's really beautiful, I didn't like the overall experience. There are way too many tourists there and way too few parking spots. And we also got scammed by a couple, minutes after we arrived (they stole our "parking ticket" and we couldn't leave the parking lot without help). We also heard from residents that there are a lot of pickpockets and many problems with tourists in general. So for me the whole experience was rather stressful and I don't need to go there any time again soon.