Police were called to a rest area about 24 kilometres south of Fort Nelson around 3:30 p.m. PT, where they discovered the man dead in a grey 2013 Hyundai Sonata.
The vehicle, with B.C. licence plate 180 LMW, had been rented in Surrey, B.C., on Monday, Sept. 30.
Investigators say the incident is considered suspicious and they cannot rule out foul play.
Anyone who saw the vehicle at any point between Surrey and Fort Nelson between Monday and Saturday is asked to contact police.