  Future smart vehicles will incorporate high-data-rate communications and
high-resolution radar sensing capabilities operating in the millimeter-wave and
higher frequencies. These two systems are preparing to share and reuse a lot of
common functionalities, such as steerable millimeter-wave antenna arrays.
Motivated by this growing overlap, and advanced further by the space and cost
constraints, the vehicular community is pursuing a vision of unified vehicular
communications and radar sensing, which represents a major paradigm shift for
next-generation connected and self-driving cars. This article outlines a path
to materialize this decisive transformation. We begin by reviewing the latest
developments in hybrid vehicular communications and radar systems, and then
propose a concept of unified channel access over millimeter-wave and higher
frequencies. Our supporting system-level performance characterization relies
upon real-life measurements and massive ray-based modeling to confirm the
significant improvements brought by our proposal to mitigating the interference
and deafness effects. Since our results aim to open the door to unified
vehicular communications and radar sensing, we conclude by outlining the
potential research directions in this rapidly developing field.
