In　this　article,　we　propose　a　physical　layer　security　(PLS)　scheme　to　secure　vehicle-to-vehicle　(V2V)　communications,　where　vehicles　share　spectrum　resources　with　cellular　users　via　underlaying　device-to-device　(D2D)　technologies.　Existing　PLS-assisted　V2V　communication　schemes　neglect　the　issue　of　the　unknown　eavesdropper＇s　instantaneous　channel　state　information　(CSI),　and　the　management　of　spectrum　resource　reuse-incurred　interference　should　be　enhanced.　Here,　we　design　an　artificial　noise　(AN)-assisted　beamforming　scheme　to　protect　the　V2V　communications　that　does　not　require　the　eavesdropper＇s　instantaneous　CSI.　Especially,　the　spectrum　resource　reuse-incurred　interference　can　be　eliminated　by　detection　methods.　Also,　we　deduce　the　expression　of　secrecy　outage　probability　as　the　security　metric,　and　minimize　the　secrecy　outage　probability　via　power　allocation.　The　simulations　demonstrate　that　the　proposed　scheme　can　reduce　the　secrecy　outage　probability　compared　to　conventional　methods.　©　2021　IEEE.