It's not that there's never been a twelve-cylinder SUV, but none are currently offered in the U.S. market and the only offerings from mainstream automakers are from Volkswagen Group divisions. Audi continues to offer the Q7 with a V12 in overseas markets, but that's a diesel. Lamborghini shoehorned the Countach's V12 into the LM002, but that hasn't been around since the early 90s.
Enter the next contender from the VW Group, coming from the division that produces more twelve-pots than any other automaker on God's green earth. Bentley's upcoming SUV is expected to borrow its underpinnings from the Porsche Cayenne (no V12 there), but the upcoming crossover from Crewe is, according to sources quoting Bentley CEO Wolfgang Dürheimer, slated to get a new version of the W-12 engine in the Continental. The Q7's V12 TDI could find its way under the Bentley's hood as well, which would be a first for the Flying B marque that has long been linked to potential diesel propulsion.