Is it true that I could lose my license for life if I get convicted of assault with a deadly weapon when the weapon is a vehicle?

Yes, if you are convicted of assault with a deadly weapon, as a felony, then your license will be permanently revoked, for life, and you may not get it back under any circumstances.

Under California Vehicle Code section 13351.5(a) states that upon receipt of a duly certified abstract of the record of any court showing that a person has been convicted of a felony for a violation of Section 245 of the Penal Code and that a vehicle was found by the court to constitute the deadly weapon or instrument used to commit that offense, the department immediately shall revoke the privilege of that person to drive a motor vehicle.

(b) The department shall not reinstate a privilege revoked under subdivision (a) under any circumstances.