It is the 'sports' version of the 625 MHC compact sedan. It features modified grille, a complete bodykit, a rear spoiler and an enhanced performance than the standard/taxi variant.
It is possibly based on the TRD Toyota Comfort GT-Z, a limited edition, high performance variant of Toyota Comfort featuring 2.0L supercharged petrol engine (instead of 2.0L LPG engine commonly found in taxi versions of Toyota Comfort).
Oddly enough, although the real-life TRD Comfort GT-Z is a limited edition car, the 625 MHC GTS is commonly found along Hong Kong expressways. It's also not for sale, meaning that Wei have to steal it in order to get one (it can also serve as emergency sports sedan for getaways).