I've studied VRP during my post graduate studies in OR and can formulate different versions of it. I also have extensive programming experience (Matlab, 6 yrs) so I can easily script the model in a function that returns the value of the cost function for given route assignments to each vehicle.
Note that I used Matlab for both my M.Sc. and Ph.D. theses (and all my publications for that matter). I also propose an extension to optimize the assigned routes using specialized algorithms, we can search for together, or some metaheuristics such as Genetic Algorithms, Simulated Annealing that I've used extensively in the past. Thanks for your time!