The deceased were identified as Naresh Kimar Barailly (55), manager of cinchona plantation at Mungpoo, and his driver Shyam Biswakarma.
Police said the two died on the spot and the two other occupants of the car were seriously injured. The car was severely damaged.
The incident occurred at around 5 PM when the car was coming from Kalimpong to Siliguri along NH-10 and the highway linking West Bengal and Sikkim was blocked.