The October issue of Motor Trend mentions that "GM insiders know they have a minor NVH problem with the new 3.6L DI V6 fitted to the new Cadillac CTS and the revised STS. And, frustratingly, they know it's a problem that can't be fixed; it's a design fault, admits one senior engineer. Wonder if they'll get a rebate from the folks who actually designed the engine for GM - British engineering company Ricardo."
Source- The Car Lounge
Things get even better as the day progresses though. The fanboys at GMI start bleating about the DI 3.6 not being as bad as the Lexus DI engine or the Audi DI engine. And now as the day ends, it's being waved off as essentially 'a characteristic of all DI engines'. Huh? Read the quoted section again- it's a DESIGN fault. The DESIGN in question is the 3.6 DI engine DESIGNED by GM. No other engines are mentioned.
Probably the most troubling part of all of this is that this wasn't caught earlier, and now it's too late to do anything about it. Since it's an issue inherent in the design, they'll just have to stuff more insulation in the CTS and STS and hope no one hears too much.