I have used it when using a trolley. Parly because they are USUALLY a little wider therefore making it easier to gets bub/kiddie in and out of the car without hitting others around or them hitting you more to the point. These days though I can hardly be bothered as I get REALLY peeved if ppl are using them and don't have kids!! Also, I don't want people denting my car (only 6 months old) so I park away on my lonesome..lol. I should also think that the extra excercise is good for me?? lol.