Digging out the Volvos today from the foot or so of snow we got yesterday, I noticed that my wife's 1993 245 had dripped some very clean looking fluorescent yellow fluid on the snow. It was located about a foot ahead of the rear wheel marks, just to the right of the centerline. The fluid was obviously fairly light as it has spread out a bit on the snow. Then my wife pointed out that my 1990 244 had left the same fluid on the snow, a bit more towards the center of the car and again slightly right of center.
The only thing I can think of is brake fluid. Gear lube and motor oil would be in a different location. It was far too fluid for grease and the wrong color for any of those three. Didn't look like antifreeze, and again in the wrong location. No smell of gasoline. And no footprints from little critters. ;-)