A modern vehicle is composed of around 100 Electronic Control Unit (ECU) connected via several types of networks. An ECU is an embedded device, similar to a RaspberryPI, running an operating system, e.g., Linux-based or real-time OS, on top of which different software and firmware may run, depending on the application. Due to the imperfection of humans, software can have faults and intrusions, which can lead to catastrophic failures that threatens human lives. A Fault and Intrusion Resilient System (FIRS) is a vehicle middleware that can mask the effect of a failure or intrusion. Contrary to Intrusion Detection and Protection Systems, FIRS ensures the continuation of the function despite intrusions. FIRS works as follows: it allows an application to run different replicas on different ECUs simultaneously. For each function executed by the application, an agreement is collected from a majority of ECUs through the (in-vehicle) network, and the corresponding output is returned. As long as the majority is not compromised, the integrity of the returned output is guaranteed despite the existence of faults or intrusions in the rest of ECUs. We have an implementation of a FIRS protocol that we are experimenting on Omnet++ simulator.