With　the　advantages　of　decentralization　and　high　reliability,　the　blockchain　is　widely　used　in　vehicular　networks,　which　has　attracted　widespread　attention　from　academia　and　industries.　However,　when　combining　blockchain　into　vehicular　networks,　there　exist　three　challenges:　1)　how　to　access　pre-deployed　blockchain　when　vehicles　are　disconnected　from　network　infrastructures,　2)　how　to　reduce　the　communication　overhead　caused　by　an　increasing　network　scale　while　maintaining　decentralization　of　blockchains,　3)　how　to　balance　limited　vehicle's　resources　and　high　throughput　of　blockchain.　To　address　these　challenges,　we　propose　an　efficient　Device-to-Device　(D2D)　Network-empowered　blockchain　framework　to　receive　and　process　transactions　from　D2D　vehicles.　We　then　propose　a　grouped　and　leaderless　consensus　mechanism　to　reduce　communication　overhead　as　the　network　scale　increases.　We　also　propose　an　elastic　resource　allocation　scheme　using　the　Lyapunov　optimization　theory　to　achieve　high　throughput　given　limited　resources.　Finally,　numerical　results　show　that　the　proposed　mechanisms　achieve　D2D　interaction　under　different　network　conditions　and　better　performance　than　existing　approaches.　IEEE