Several years ago I was involved in treating an apartment suite for bed bugs. The bugs had been discovered and treated relatively quickly but the tenant then failed to cooperate with all instructions. The tenant abandoned the bedroom and slept on a chair in the living room and, when that became uncomfortable, slept in his van on the parking lot. The tenant alternated between sleeping in the van and the chair. We treated this suite numerous times over the course of a year and a half and could not get rid of the bugs. We heat sterilized the bed and protected it with combination interceptor/gluboard traps but the tenant refused to sleep on the bed.
The chair on which the tenant slept had climb up interceptors under the legs and we constantly found a dribble of bugs in those devices. All the furniture had been thoroughly treated numerous times and live activity was never noted except in those interceptors. At one point during the middle of winter (a winnipeg winter) it appeared we finally got rid of the bugs. But when it warmed up in spring the bugs came right back and once again we could not get rid of the bugs despite countless chemical treatments. The tenant finally moved and the infestation went with it. That suite has now been bug free for several years.
I questioned the caretaker about the tenant’s sleeping patterns and it appeared the tenant gave up sleeping in the van when the weather was very cold. This cold period just so happened to be when the bugs stopped being caught in interceptors in the suite. My suspicion was that the van was thoroughly infested and as long as the temperature in the van remained below 13c the bugs would not move. The bugs would also burrow into the seats and carpets which would be difficult to heat during short drives to work which ensured the bugs remained immobile until spring. As soon as spring time came the bugs reactivated and hitched a ride to the apartment on a continual basis.
I have also noted other cases where persons with severely infested homes immediately put a for sale sign on their vehicle when it became known the vehicle was also infested. Beware the infested used car!
You can address bed bugs in cars with commercial heaters from exterminators. You might also try leaving the vehicle parked in the sun with the windows closed on the hottest summer days. The temperature in a vehicle would approach 180f which is more than adequate to kill bed bugs. The trick is to ensure all the areas under and between seats are heated to a minimum of 122f which is more difficult. You might put thermometers in the most insulated spots to monitor success or failure.
My father, a long distance truck driver, also had his own method of killing “bugs” in his truck. My dad was bothered by the smell of the previous driver in the bunk so he parked his truck in the sun on a hot day with the engine running and the interior heater on all day. The smell was probably caused by mould or mildew which is killed at about 150f. The smell disappeared after super heating the cab of the truck so I suspect 150f penetrated to all the mouldy areas. Given that bed bugs die at 122 that seemed like a nice trick. The power of the sun was enhanced by mechanical heating of the engine which normally operates between 175f and 195f.
Be warned, however, that leaving a vehicle idling in the hot sun could cause overheating because there is no air flow over the radiator. An overheated engine is ruined and a new engine costs 4-7 thousand dollars. I would suggest avoiding this method unless you have some mechanical experience and can ensure the overheating issue is avoided.