The third-generation Audi TT managed the four-star rating chiefly due to a "lack of latest advanced technologies such as autonomous emergency braking," a release from Euro NCAP claimed.
"This important technology is becoming more common and is already available on many other models in the Audi range," the release read.
That lack of autonomous emergency braking lead to the TT scoring 64 per cent in the safety assist category, while it scored 68 per cent for child occupant safety (mainly due to a selection of child restraints not fitting in the two rear ISOFIX-enabled seats). It scored 81 per cent for adult occupant protection, and 82 per cent for pedestrian protection.
By Euro NCAP's own declaration, the TT - which is equipped with dual front and front side airbags, and electronic stability control as standard - managed an "overall good performance in crash protection", which is the same as what is required to attain a five-star score. But the car's lack of "robust crash avoidance technology" saw it penalised.
CarAdvice has contacted Audi Australia for comment.
For 2015, Euro NCAP has introduced new rating rules and updated testing procedures, along with revised crash test dummies.
The new crash protocols include a full-width barrier frontal test, which specifies "a small female driver and rear seat passenger".
Euro NCAP secretary general Michiel van Ratingen said: "The scores obtained in the new full width impact test will provide further information on how safe occupants of different stature really are and will provide an incentive to improve the restraint systems in cars."
Other cars tested in this round of Euro NCAP ratings included the all-new Renault Trafic van and its twin under the skin, the Opel Vivaro - both of which were tested in people-mover specification, and both of which managed just three stars.
The two scored identically in each of the separate criteria, including a poor showing for adult occupant protection (52 per cent) and an excellent child occupant score of 91 per cent. Both scored 57 per cent for safety assist technology and 53 per cent for pedestrian protection.
The Renault will go on sale later this year, albeit in commercial van specification only, while the Opel, badged as a Holden, could arrive here in 2016.