I just got back from my brother-in-law's military retirement in Norfolk, Va. My wife and I drove up last Thursday night, came back today, towing our little trailer. With luggage, et al, in the trailer, total weight, I would guess, to be about 300 to 350 lbs. Did not much hinder the smart at all, and we averaged about 41 mpg for the weekend. Coming home in high head-winds (15-20, with higher, swirling gusts) was a bit of work, but the trailer didn't negatively impact the drive. Pic is below (click for larger image):
