According to Tata, the XJ’s lightweight aluminum structure makes it over 300 lbs. lighter than a bodyshell made from steel. In fact, at between 3,800 and 4,300 lbs. (depending on the specific model), the new XJ is lighter even than its steel-bodied stablemate the XF—despite being six inches longer. Compared to the chief rivals in its class—principally the BMW 7 series and the Mercedes S-class—the new XJ is between 300 lbs. and 570 lbs. lighter, according to company officials.