I think a single umbrella stroller would probably fit in the frunk and also the trunk with the third row folded up? I don't have one so I can't test it. But this is my travel stroller in the car. It won't fit in the frunk because it folds in half, but you have two options for it in the back of the car: 1) standing up in the lower storage, or 2) flat like you would place it in a normal SUV trunk. The stroller is the Valco Snap - its dimensions when folded are approximately 20.5"W x 30.5"L x 14"H. The lower cargo area is pretty deep, so even if an umbrella stroller doesn't lie horizontally with the third row folded, I think it would fit vertically in the cargo area behind the third row. Hopefully that makes sense!