I usually leave DD in the car. Seriously, by the time we negotiate into the servo, I herd her away from all the temptations, I pay for the fuel, safely negotiate back to my car, wait (im)patiently for her to get into the car (because she has to climb in herself because we can't possibly let Mummy lift us in when we're in a hurry!), get in and leave - 6 cars could have filled, paid and left!!!! So, some days, for my sanity, DD's safety, and the tempers of fellow fuel station users - it is just easier to leave DD in the car with the car locked!