I have just returned from UK to BG trip (arrived back 11 July) My route - Calais-Brussels-Gent-Aachen -Koln-Frankfurt- Wurtzburg-Nurenburg-Regensburg-Lintz-Wein-Gyor- Budapest-Szeged-Arad-Deva-Sibiu-Pitetsi-Bucharest -Constanta -Into BG
Roads from Calais right through to Arad mainly motorway, From Szegred to Arad new motorway and new large border control, (Full vehicle and Docs check, from there down to Arad new motorway, Just after Arad and towards Deva some normal but good moving country road, at Deva New motorway bypassing Sibiu to the Transalvanian mountain pass route (Motorway scheduled to pass through this at some point) down to Pitetsi,
Major roadworks about 5km from Pitetsi just before joining the Bucharest motorway, resurfacing the road one side at a time, so I had nearly and hour stop start passing through.
Other area's to watch, Brussels to Gent-on entry to Gent 3 lanes down to one over about 10km stretch, long tailbacks.
Several areas of roadworks through Germany especially from Koln right down to Lintz.
I did most of the long stretches through the night and main chunk of Germany on a Sunday.
No real need for Sat Nav for the main route as long as you know your 'Target' towns/cities, they are well signposted at each one.
Hope this helps somewhat, the way they work it could all change by the time you travel???? safe trip