[Waky]

Try this out:

--OnEvent (Panel 1):
if event == "UNIT_ENTERED_VEHICLE" then
	if (CanExitVehicle()==1) then
		self:Hide()
	end
elseif event == "UNIT_EXITED_VEHICLE" then
	if (CanExitVehicle()==nil) then
		self:Show()
	end
end

--OnEvent (Panel 2):
if event == "UNIT_ENTERED_VEHICLE" then
    if (CanExitVehicle()==1) then
		self:Show()
	end
elseif event == "UNIT_EXITED_VEHICLE" then
    if (CanExitVehicle()==nil) then
		self:Hide()
	end
end

To my understanding it's exactly what you said would be wrong, that event listens for anyone to enter/leave a vehicle so it'd be going crazy on and off without you.

Lemme know if this works!