Travel from Salzburg to Frankfurt

Rent the car in Germany, not in Austria. If you rent in Salzburg, you will pay a big fee because the car will have to be transported back to Austria before it can be rented again and you will pay the costs of that and then some. There are rental agencies just over the border from Salzburg. Remember, 6 adults with luggage is going to require a mini-van, and they can be expensive.

I am seeing a price of 108 EUR for your group with a Sparpreis Gruppe ticket for early June with a single connection in Munich. You have to buy the ticket now.

Rent the car in Germany, not in Austria. ... There are rental agencies
just over the border from Salzburg.

I've spent over 160 nights in Europe from 2000, all but 6 nights of it in Germany, and most of that in Bavaria. I've never rented a car. I always found I could get to where I wanted to get to using public transportation (trains and buses). And 85% of my nights have been in towns under 20,000.

So I don't think a car is the best way to get from Salzburg to Frankfurt, but, none-the-less, if that's what you want to do, I'll help you out. There is a Europcar office across the river in Freilassing, Germany. If you will be staying in Salzburg old town, take the #24 bus from Ferdinand-Haunch-Platz, direction Freilassing, Sonnenfeld. Get off at Freilassing, Salzburgerplatz. The rental car office is across the street to your left on Ludwig-Zeller-Straße.

Since the plan for Frankfurt is just to sleep there, I don't think I would leave Salzburg early in the morning. I'd want to get there by around 7 or 8 pm, but you can do that after a mid-day meal in Salzburg by using the 14:00 - 19:44 DIRECT ICE train between Salzburg and Frankfurt Hbf. There's a restaurant car on this train - I'd probably just bring some sandwiches etc. and picnic/snack on the way to Frankfurt. The earlier train trips which you might have been considering necessitate a change of train on the way, which is less convenient for sure.

Russ is right. For the number of people in your party, with luggage, the ICE is the way to go. No need to get off and transfer, and faster than you can drive it by hours. Plus it takes you straight to the airport, which is where you want to stay if you have a morning flight.

It may be more expensive than the regional trains, but it's a much better ride. and cheaper than renting a large van and driving. Don't forget you'll be paying for fuel ($7-8/gal on the autobahn).

Plus it takes you straight to the airport, which is where you want to
stay if you have a morning flight.

The direct journey is indeed what you should shoot for. But I'm not sure where you want to stay, exactly.

Your stated destination from Salzburg was just "Frankfurt", so I looked only at ICE trips to Frankfurt Hbf, the main station in Frankfurt, as the destination. The direct journey I suggested, ICE 116 departing at 14:00, terminates at Frankfurt Hbf (17:49) and does NOT stop at FRA airport.

It is of course possible to stay in Frankfurt proper (where a greater number of lodging options is available) and in the morning catch the S-Bahn from Frankfurt Hbf to the airport in just 12 minutes.

OR, if you have chosen an airport hotel, you could transfer to the Frankfurt Hbf > Airport S-Bahn right after you arrive there (20:02 - 20:14, for example.)

Having now just now taken a look at the Salzburg > FRA airport options, I see no DIRECT service for this journey. Maybe I am missing something and KGC or someone else will pop in with details on this mystery train.

Having now just now taken a look at the Salzburg > FRA airport options, I see no DIRECT service for this journey. Maybe I am missing something and KGC or someone else will pop in with details on this mystery train.

It depends on the exact travel day. There is a direct train, ICE 118, showing on the particular day I am looking at, June 10. The other factor is cost, especially when comparing with a van rental. The direct ICE is the single most expensive train Itinerary that day, at over 300 EUR for the group with a Super Sparpreis ticket, while taking a single connection in Munich is almost half that price.

So... for the direct trip to FRA airport (12:00 departure from Salzburg in this case) which Sam has located, you'd need to make this trip before June 14; this train doesn't run after the 13th.

As for your controlling expenses on this day before your flight... much depends on the cost of your final night's lodging as well. I'd total up both the transport AND the lodging expenses in Frankfurt proper vs. at Frankfurt airport.

A 3rd option for overnight: Mannheim is just 30 minutes from FRA airport by ICE. Perhaps lodging near the station there would work in your favor economically.

If so, you might buy the train ticket to Mannheim (Salzburg > Mannheim, 14:00 - 19:25 direct trip with that same ICE 116 I mentioned previously.) Then in the morning, it's a 30-35-minute direct train ride to FRA. Between 6:30 am and 9 am there are 5 different ICEs that make this trip. You can ticket both the Salzburg > Mannheim + Mannheim > FRA airport legs at the same time by using the "stopover" feature when doing your search at DB.

Van rental is going to be much more than 300 euro. Fuel alone is going to be over 100 euro. Drop off fee will be high, since it's not an in country rental. Take the train. Even if you have to transfer at the main HbF it's going to save money and time.

The drive from Salzburg to Frankfurt takes at least 7 hours, hands on wheels. And if there is any of the almost happened traffic jams, it could take much longer. Therefore a car really is not a good decision. Take the train instead.

Thank you everyone for you helpful suggestion which have convinced us to take the ICE to Frankfurt Htf - we are not staying near the airport.