highlight reflections with white plane or vray light plane?

what do you think is better to use for highlight reflections on cars or other metal surfaces, white planes with vralight material assigned or just vray plane light?

I would say a simple plane would save a lot rendertime compared to a light!
And in reality you often have not got multiple lights reflecting (you just have one sun), the objects causing reflections mainly are light surfaces (houswalls, …)