  Internet of vehicles (IoV) has emerged as a key technology to realize
real-time vehicular application. For IoV, vehicles adopt cellular
vehicle-to-everything (C-V2X) standard to support direct communication among
them. C-V2X mode 4 controls resource allocation without the assistance of
cellular network, hence it is widely used for IoV. However, C-V2X mode 4 has
two drawbacks. First is that vehicles cannot communicate with each other for a
period in some case which will cause an increase in age of information (AoI);
second is that vehicles may select resource already occupied by others which
will deteriorate the reliability. To address the two drawbacks, we propose an
enhanced C-V2X mode 4 to optimize AoI and reliability. In addition, we consider
the fact that for most vehicular applications, each vehicle periodically
requires fresh information of vehicles within a certain distance and propose a
new performance metric to evaluate the system AoI for IoV. Furthermore, we
construct a platform through integrating SUMO and NS3. We demonstrate the
superiority of the enhanced C-V2X mode 4 base on this simulation platform.
