A real life city bus from Greece, the Volvo SB756. Designed in late 1970's by Sarakakis Company, it was loosely based on Volvo B10M chassis, but built completely in Greece. "SB" means "Sarakakis Brothers". Powered by a THD100 series Volvo diesel with ~300 hp and a close ratio manual gearbox, the SB756 became a legend for its speed. ERAP (ΗΣΑΠ, Ηλεκτρικοί Σιδηρόδρομοι Αθηνών-Πειραιά, also appears ISAP in internet) was the first operator, with about 100-120 built in 1980-1981. They replaced older bus types which in turn had replaced the discontinued tram network together with trolley buses. The SB756 was exported as well in Middle East in 1980's.
It was said that the SB756 was thirsty, but ISAP did not care much for that, because all routes these buses served were very profitable, especially the line Athens-Piraeus (Syntagma Square-Piraeus Port). Personally I traveled in them in their last years (1998-2002). I had asked about horsepower several drivers, all said "around 300 hp", not remember if they had 5 or 6 speeds however. The only Volvo engines fits are the THD101KC (307 hp/2,200 rpm and 1,215 Nm/1,400 rpm) and the THD101KD (285hp/2,200 hp and 1,200 Nm/1,250 hp).
There was also an articulated variant, nicknamed "Dinosaur" because its 18m length, first designed from Thessaloniki in 1979 and came in Athens in 1981. The last Sarakakis "Dinosaur" buses in Athens withdrawn in 2005. These had a five speed Morse automatic gearbox and I remember that they were as much fast as newer Mercedes O405GN (articulated) despite their age.
And a video, perhaps some of you remember the SB756 bus or even traveled with them, if visited Athens.
P.S Thanks a lot to Nestin, I used his Ikarus buses as design base. Passenger doors and rims are almost the same (Greece did had Ikarus as well, the Hungarian built Ikarus 260 in real life). Tried as much I could to be close from photos. Note that these were high floor city buses.