Whereas sherry casks impart grape flavors to the whiskies aged in them, bourbon butts flavor whiskies with hints of coconut. These retained flavors make older casks even more valuable than newer ones. King Car sends buyers to Spain and the US every year to acquire replacements, though selecting them is something of an art.
金車進口的雪莉桶曾釀造過雪莉葡萄酒，因而熟成出來的酒有酒桶留存的葡萄味；而釀造過威士忌的波本桶，則有「前身」椰子風味，也因為這些珍貴「遺風」，因此酒桶是老比新值錢，如何選購也是一門大學問，金車每年都要派專人到西班牙、美國選購二手橡木桶。