Rental Car Salzburg to Innsbruck

Definitely return the car to a location in Austria, not Germany. Cross-border rentals can have enormous dropoff charges.

If you need an automatic, you need to pickup the car in a large rental car location. Chances are they'll have more automatics. I also agree about picking up and leaving in Austria. Make sure you purchase the vignette window sticker for the time you're going to have the car.
We've traveled your route a few times over the years, and you are going into places of extreme beauty. We always see much more by automobile when traveling in the mountains. We love to get up on the mountainside and travel from village to village.

On various trips, we’ve rented from Sixt, Europcar, and others. Europcar has been our most frequently used rental company - great prices, good locations for pickup/drop off. Sixt is definitely the company to use if you’re looking for a BMW, Audi, or Porsche, although they offer other makes, too, if you’re not specifically looking for a high-performance German vehicle.

We've had more problems with Hertz in EU than with any other.
EU is compact. Go for the smallest car that will carry you and your luggage.

A few comments on what has been said above and a few comments of my own...

Any car rented in Austria will have a Vignette toll “sticker” attached. It should be noted that Austria has moved over to a digital vignette, which is tied to the license plate of the car. It is very likely your car won’t have a sticker, but will have a digital vignette. Check with the desk agent so you don’t spend unnecessary money.

Next, we always use Sixt. They are not, however, limited only to German high end cars. They offer the same cars as all the other rental places. We use them because their locations are convenient for us and we have a membership card.

I think your plan is good. Finding places to stay on the fly, however, is an idea from 20 years ago. You might want to consider making some of your reservations online in advance rather than spend a few hours each day trying to find a place to sleep. I can probably count on one hand the number of Zimmer Frei signs I’ve seen in the past 12 years. Very different from my trip in 1988 to Austria.

I used Hertz for pickup in Salzburg and drop off in Innsbruck in 2014. The Herz location near the Altstadt did not have automatics (I also do not drive manuals), so I had to catch a bus to the airport to pick up the car. The car already had a sticker vignette (pre-digital days); the counter agent told mentioned this at the time of rental.

Thanks everybody. I think we should just plan to pick up at the Salzburg airport & I’ll see who has better deals Sixt or EuroCar couple days ago it was EuroCar.

Glad for the advice about booking accommodations ahead...we were planning to “wing it” that used to be the way to do it. Glad for the heads up that it’s very recently changed a little with regard to that.

Let you all know how it goes