I have no doubt that what's in your Citaro is either an OM 906
hLA or OM 457 hLA.
And to clear your other issue up, all OC 500-series chassis
products are manufacturered in Sámano, Spain at Evobus
Ibérica. The Brazillian chassis for heavy urban low-floor
buses are designated O 500 U (articulated version is O 500 UA).
Go to Mercedes-Benz Online Services for the latest technical
broschuren...
http://www.mercedes-benz.de/content/germany/mpc/mpc_germany_website/de/home_mpc/bus/home/services_accessories/services_online.html
Hmm, I thought Mercedes (and MAN) used the letter G to mean
bendy in their nomencleture. The UA designation sounds so
Scania-ish.
BTW, did you read about the latest news in PerthNow regarding
new buses for the city? I feel they are bringing more Mercs yet
again. Think they should consider B9Ls for a change.