No results are counted for close combat against vehicles. The vehicle simply moves away as it wishes in its next turn, while the troops who mounted the assault are free to move, shoot etc normally. Thus assaults against vehicles are very easy to work out – just make your attacks and work out any damage.
Errata — Chapter Approved: Main Rules Clarifications (v2.0): A unit may not advance or consolidate after destroying a vehicle with no WS characteristic, in an assault.