Not sure how it was before, but the current models definitely do not draw what the names suggest. They seem to use the added up maximum theoretical wattage of the LEDs for making that. Since your light has 3W chips i assume actual wattage will be 1/2-1/3 of max. So if it says 180, its probably less than 90. If it says 300 its probably less than 150 etc...
Ive some UFOs - not mars, but theyre all the same those first generations - and they can grow plants. But really youll want something like 100W actual draw per plant. And good spectrum, with some white and IR in there, or additional CFL lights.
I have a 125W panel that works great for a single plant (with fluorescent side lights), as good as 200W HPS, though different (buds and growth definitely not as dense, leaf structure is much lighter/smaller under LED). But its still great weed if you have good yield!