The aim of this paper is to propose a new event-based mesoscopic approach to model multi-class traffic flow on multi-lane road sections. The mesoscopic model was first proposed by Leclercq and Bécarie (2012) and turns out to be equivalent to the resolution of the seminal LWR model in lagrangian-space coordinates n − x. It is fully consistent at a macroscopic scale with the LWR model while keeping track of individual vehicles. Our model is built on Hamilton-Jacobi equations which have been proven to provide an efficient framework in traffic flow modeling for exact numerical methods at a low computational cost. The paper revisits the multi-class problem with a continuous moving bottleneck approach (instead of a sequential one), introducing a capacity drop parameter for multi-lane sections. It also overhauls the Daganzo diverge model with a relaxed FIFO assumption.