[ProblemFactory]

Three people in the back seat is a couple hundred kilos.

Modern cars, including the XC90 have a tilt sensor to adjust the headlights automatically for this.

[avs733]

three people in the back seat are in front of the rear wheels/basically over the rear suspension. Its a different moment arm to have it in the trunk or on the roof.

Source: I teach statics

[snovv_crash]

If you taught Dynamics you would know that the compression of the rear springs caused by most of the weight being over the back wheels would make the lights point higher.