I live in Munich. Couldn't find numbers for the metro area, but I found numbers for Bavaria. It seems that Google's electricity usage has grown to the point where it uses more than half as much energy as the Bavarian car-using commuters do. Still less, but more than half. (This counts only trips between home and work and only those by car, and the number is decidedly imprecise.)

So at this point, I assume that Google uses more power than the Munich metro-area single-car commuters, even for the widest definition of metro area (the widest I've heard spans 6m people, four times Munich's own population).

Is this reasonable? Is it reasonable that a collection of services with >1B users uses more energy than the single-car commuters in a metro area like Munich? I rather think so. (But then I don't have a high opinion of the value of driving to work.)