I would advise you against using LOWW. Their fees are very high, as they neither want nor have significant GA traffic apart from bizjets.
There are 4 GA airfields around Vienna – LOAU, LOAS, LOAV and LOAN. LOAS is rough grass, the others are hard surface. LOAV and LOAN have RNAV approaches, in LOAU you may be able to use the nearby military airport of Tulln (LOXT) for cloudbreaking.
Personally, I’d suggest using LOAV or LOAN, with LOAV being about 20 km nearer to Vienna. If you just want to stay overnight without any sightseeing or things like that, there’s also a motel immediately next to LOAN.
Parking may can be a problem! Somebody can ask the airport?
I have just emailed them, with a link to this thread.
Personally, I’d suggest using LOAV or LOAN, with LOAV being about 20 km nearer to Vienna. If you just want to stay overnight without any sightseeing or things like that, there’s also a motel immediately next to LOAN.
This is the hotel. I’ve stayed there many times myself. It’s basic accomodation, but perfecly clean and in good condition. Just not a lot to see within walking distance.
Link
I’m looking at the IFR routings from Lelystad EHLE to Mali Losinj LDLO.
GC distance is 590NM. Found a route over airways which is 627NM (6% overhead, which is very good).
With the long-range tanks in the DA40 I could do it in one leg (about 4,5h flying assuming zero wind and 140kts TAS at FL150).
The route:
EHLE NYKER/N120F070 IFR L620 SONEB Z841 DOMEG Z841 BIGSU/N140F150 L603 OLETU Z106 BAVAX M867 NOKDA Q100 ARNOS P125 URAVA L607 CRE CRE3C LDLO
EHLE ELPAT/N0130F090 IFR L620 ARNEM/N0130F100 SONEB/N0132F140 Z841 MEVEL DCT REDSU DCT ERNEP DCT TOBAK DCT GEDSI DCT LEPSA DCT TAKUT L603 DINKU/N0135F150 AKANU/N0136F160 LUPOX/N0138F170 OLETU Z106 BAVAX M867 NOKDA Q100 ARNOS P125 URAVA L607 CRE CRE3C LDLO
5% over GC 
However you may want to play with fly-through waypoints, to get different MEAs, for aircraft performance or desirable-scenery reasons.
Since Germany allows DCTs (with certain limitations) it is always possible to reduce the overhead by a few percent if one really invests some effort and headache into the routing. In reality though, it doesn’t pay off. The routing effectively flown will be the same. German ATC are not really interested in the flightplanned routing; they work “tactically” and will thus clear aircraft based on actual traffic, military areas and a few other factors. If anyhow possible, they will try to clear direct all the way to the FIR boundary (and often further down the route, after coordination with the adjacent ATC unit).
I hope to make this trip to LDLO on the proposed dates. To save going through all the posts again, can somebody advise me what is the lowest IFR alps crossing (Austria)?
Many Thanks
If you fly Munich-LDLO you can cross IFR at FL150. If you fly a bit more west (Graz-Zagreb) you can cross at FL120, I did that once last year.
Thank you alexisvc.
