Car-to-car communication is attracting significant attention as it promises to drastically reduce road fatalities, improve mobility and enable a high-level of vehicle automation. Supporting safety critical applications is at the core of car-to-car communication, and for years, the technology of choice for V2X has been IEEE802.11p. Recently, a new standard addressing V2X applications has started evolving under the umbrella of 3GPP, whose focus is mobile broadband standardization. Because the safety of millions of road users will depend on the performance of these technologies, it is important to compare them. Read this paper to learn more.