The MB O405 was never intended as a coach. In the beginning of
the 1980s, the German Ministry of Transport promoted the
development of a new modern city and intercity bus. In response,
Mercedes-Benz presented the 11.5 metre long O405 citybus in 1983.
Production for the series started in 1984. The O405G was presented
in 1986. The low-floor versions, O405N/O405GN were presented in
1989. These were further improved in 1993-94, by having its seats
in the front section lowered so that it is attached to the floor
and not on platforms like its predecessor. The new variants are
called O405N2/O405GN2.
The B10M, on the other hand, was developed as a multi-purpose bus.
It is suitable for city, intercity, suburban or interstate
services.
There was a thread about the weight of buses and I had posted the
unladen weights of a B10M and an O405 (sourced from the SBST
webpage), which are:
B10M Strider: 10370
Mk III : 10300
WA O405: 9550
It is clear that the B10M is not lighter than the O405, nor does it
have a light chassis (unless you consider 10 tons as light?) as
claimed by our chicken friend. So, I would suggest our friend to
stop embarrassing him/herself further. The superior man,
recognising his faults, corrects them. 
