I think the older Tesla system (HW3) was around 300w, but I think the newer system is more now as they beefed up the compute, but I haven't seen a number on that. The old system is pretty much maxed out though with no room to grow other then making things more efficient vs just more raw power usage.
A lot of the older hardware back then wasn't purpose built for driving and was more repurposed general graphical compute, so it was less efficient hence the 2Kw you were seeing. Tesla built ASICs for the driving computer to bring costs and power usage down.
With the newer purpose built Nvidia stuff I'm sure that has brought the power draw down a lot though, likely relatively close (better or worse I don't know) than Tesla's watt per performance.
edit: clarity