Justin Bieber -- Speeds Off in White Lamborghini

With Lil Za getting pulled over all over town in his white Ferrari, Justin Bieber broke out his white Lamborghini in Beverly Hills on Saturday night ... and showed he's no better a driver than his friend.

Bieber made his way out of Crustacean and our photog tried to ask him about our story ... about how there are photos going around of Bieber partying with sizzurp ... but he ignored it completely.

Once Biebs got his car from the valet, he pulled into the street and then GUNNED IT as he drove off.