I'd certainly rather go with a 105mm HE or HEAT round. But if all you have is a M16A2, it works for me.
It'd help if the rifleman has a little elevation, about turret roof height or a little more.
In the story as written the Panhard is on a very steep slope, a jeep trail in cliff terrain, working to get around a stopped troop truck, so very vulnerable. I think a lot of armored vehicles are susceptible to rollover, so if the driver’s hatch is up he’ll be looking way out for the best view. And that side hatch doesn’t look quick to close, and it might force the driver to extend his exposure while he tries to close it (as opposed to just ducking inside.)