At least for my MY16 XC90, the VOC temp is the outside air temperature where the car is located based on the nearest reported temperature for my area.I believe the temperature at the car is the external temperature.
This can be confirmed by looking at your weather app on your phone.
- My car is in a heated garage at 50°F.
-The nearest city’s weather OAT is reported as 30°F.
-The OAT at my home is 29°F.
VOC shows 30°F.
Having VOC poll and the car report OAT from the vehicle’s temp sensor or the interior cabin temp may risk an undesirable battery discharge.
All the best from Minnesota USA,
A fine MY16 XC90 T8