This paper presents NETCARBENCH, a benchmark devoted to improve the assessment, the understanding and the comparability of techniques and tools used in the design of in-vehicle communication networks. This benchmark is motivated by the increasing use of algorithms intended to optimize the resource utilization in the design and configuration of automotive communication systems. For instance, typical objectives are the minimization of the network bandwidth usage and the reduction of the worst case response times of the frames. The main contribution of NETCARBENCH is to allow a fine grained user-defined parameterization of the generated message sets by means of XMLconfiguration files that specify the characteristics of the message sets and the variability thereof. Experiments suggest that the outcomes of NETCARBENCH are satisfactory in terms of their closeness to the input specifications. NETCARBENCH and its user manual are freely available under the GNU General Public License.