Online map programs are always estimates, however all the numbers you have told us about from the map24 site seem very very high. I don't see any reason why that trip would take 8+ hours.

Google's estimates are often optimistic, but can certainly be hit or miss. 5 hours for this trip seems in the ballpark. As Larrison said, 4.5 hours is about the best possible time you could cover that distance, but that would assume driving at or a little above the speed limit with no stops, if you stop a time or two, I'd say 5-6 hours sounds most likely.