I am pleased to find out that by changing the value of BehaviourRetire bool from true to false in the file ai_driver_config.xml, the driver will stay in the immobilized car longer and could even be there until the race is over. Enjoy !
<behaviour>
<BehaviourRecovery bool="true" />
<BehaviourRetire bool="true" />
<BehaviourHeatVision bool="true" />
</behaviour>
<behaviour>
<BehaviourRecovery bool="true" />
<BehaviourRetire bool="true" />
<BehaviourHeatVision bool="true" />
</behaviour>