Grab your suitcase, walk out of arrivals at Cambridge Airport (CBG), and pick up your rental car. Which one you jump into depends on where you plan to go. If you’ll be mostly driving in downtown Cambridge, around 2 miles from the terminal, consider something small and zippy. A compact car that’s fuel-efficient will be perfect for navigating those busy city streets. But with a wealth of things to see, like the stunning rocky coastlines of the surrounding region, you’ll probably be clocking up a few miles. A larger vehicle, like a full-size car or an SUV, will make lengthier road trips a pleasure.