We just did a 1400 round trip in our "new to us" 2017 Escape. Great ride. However, about an hour from home we went thru a pretty good snow storm. Nothing too bad, just snow and some mixed freezing rain. We stopped for a reststop break about 50m from home and when we started up slowly I heard a strange rumble from the back of the car. You don't really hear it when we're moving fast. We then got into regular stop and go, waiting for lights, etc., and each time starting slowly, there's this rumble. That's the only way I can describe it. It goes away (or you can't really hear it) after acceleration. It's been 24 hrs, we're going to take it to the car wash and run it thru. I checked underneath and can't see anything (I was thinking it might be a plastic bag or something. It is horrific how much trash is on the highways these days). Or, maybe clumps of ice? The only thing I see is there is a plastic? cover toward the back that is bolted on, but there is a gap between it and whatever it is bolted to ... and three out of four bolts hold it on ... I plan on taking it to our mechanic to have him look under, but any ideas as to what it might be?