Format of vehicle routing problem instances :

Number of customers, best known solution value
Vehicle capacity
xdepot ydepot
For each customer : Customer number, x, y, demand

Few files also have one or two solution at the end.
The format of solutions is :
Number of vehicles tours, service time for each customers, tour time limit
For each tour : number of customers, 1. customer, 2. customer, ...

Sources of the best solutions known :
L. Gambardella,  É. D. Taillard, "An ant system for the VRP", in preparation.

A. Reinholz, http://www-set.gmd.de/~andy/Benchmarks.html

Y. Rochat, É. D. Taillard, "Probabilistic diversification and intensification in local search for vehicle routing". Journal of Heuristics 1, 1995 147-167. 

É. D. Taillard, "Parallel iterative search methods for vehicle routing problems", Networks 23, 1993, 661 ­ 673.