The quadricycles are reckoned as an intermediate step between the three wheelers (Piaggio MP3 – Quadro etc) and the small urban cars (Smart etc). However the result of the latest Euro NCAP tests on four  heavy   quadricycles (Renault Twizy 80, Tazzari ZERO, Ligier IXO J Line 4 places and Club Car Villager 2+2 LSV) are disappointing. 
The quadricycles were safer than a motorbike, much more unsafe though compared to normal cars, even low – cost vehicles.

The quadricycles are divided into light (limited to 45 km/h - 28 mph) and heavy ones which are not limited to their top speed. Some of those may reach 100 km/h (62 mph). The Renault Twizy got the highest score from the four vehicles, with 6 points out of 16 on these special quadricycle standard tests. 

Comment: Generally speaking, size matters when it comes to contemporary four wheeler safety.