Get your luggage, exit Portsmouth, NH Airport (PSM-Portsmouth Intl.), and pick up your rental car. Which one you jump into depends on where you’re going. If you’ll be mainly driving in downtown Haverhill, around 25 miles from the terminal, consider something small and zippy. A compact car that’s fuel-efficient will suit those busy city streets. But with almost endless things to see, like the picturesque sandy shores of the surrounding region, you’ll probably be racking up a few miles. A bigger vehicle, like an SUV or a full-size car, will make lengthier road trips a joy.