Thanks for your prompt reply! I'm flying in to New York and then driving up to Montreal and Quebec City, before heading to Toronto and then back to New York. I can't wait! By the way, it's MAKE the most of your trip. Thanks again.
Yes, you're right. "Fill her up!" is ridiculous and I said it as a bit of a joke. It's a bit of a cliche that probably comes from old films, I don't think anyone would say it seriously. It is (or was) traditional to refer to cars, boats and countries as "she".