That's a photo of these buses.
Short, square, with wheels on the corner, quick acceleration and low speed, you will see its qualities shine in the movie.
Soundtrack Vasco Rossi's Siamo Soli
Note added 2016
I had enormous difficulty then, trying on foot to work out the route, but more recently with the google map and street view, I have worked out that that movie runs (I think) from St Eustachio (where Michelle Obama was taken for gelato) down to S.M. sopra Minerva with the wonderful elephant obelisk, then Via del Pie di Marmo, Via del Collegio Romano (also see this) round through the wonderful Piazza Sant'Ignazio, hastening through the Piazza di Pietra without any courteous nod towards Hadrian's Temple then coming to a halt in via dei Bergamaschi at an entrance to Piazza Colonna (also see this). Though this bus route no longer runs, this remains a wonderful walk.... or rather, is indicative of the quality of walks through any number of streets in the centre of Rome.
Some photos from pages linked above
|Bernini's Elephant and Obelisk in front of the Basilica Santa Maria sopra Minerva|
|Piazza Colonna, seat of the Italian Government.|
"The column [colonna] was built and dedicated to Marcus Aurelius after the emperor's death in 180 AD.
In 1589 Pope Sixtus V restored the column and freed it from any pagan significance
("ab omnia impietatem expurgatam") by placing a statue of St. Paul on its top."