This is a feature that I have never seen on any other navigation or journey planning app.

Navigation apps always give an ETA - Estimated Time of Arrival. But how accurate is it really? That depends on traffic, traffic lights, one-way systems, etc but what is not considered is your own vehicle's top speed! Of course learner drivers/motorcyclists can't take motorways but can a(n unmodified) 50cc moped/motorbike attain 70mph on a dual carriageway or 60 on a single carriageway? I know the only time I managed 70mph on my Honda CBR125 was going downhill!

There needs to be an option to set your own vehicle's top speed and power which will vastly affect your ETA and overall journey time.