Tank up Definition 1 of 2Pro Tip 1/3Prepare for Journeys Used when intending to ensure sufficient fuel for travel without stops. Let's tank up now so we won't have to stop later. Pro Tip 2/3Not Just Cars Can apply to any vehicle with a fuel tank, not only cars. We need to tank up the boat before we set sail. Pro Tip 3/3Full Capacity Implies filling the fuel tank to its maximum capacity. I always tank up my motorcycle before a long ride.