Back when GM’s then-future HF V6 engine family first became public knowledge (circa 2000), a twin-turbo 3.6-liter capable of 360 horsepower was part of the plan. Then Bob Lutz put a 400-horsepower 6.0-liter V8 in the 2004 CTS-V instead.

The second generation CTS-V got a 556-horsepower supercharged 6.2-liter V8, opening up a huge gap in the line as the next engine down, a naturally aspirated 3.6, produced just a little over 300 horsepower. A turbocharged 3.6 seemed a most logical candidate to fill this hole, but didn’t happen. Instead, a turbocharged 2.8 (also part of the original plan, IIRC) capable of only 300 horsepower was offered in the 2010 SRX, only to be discontinued after only two model years due to a combination of its high price and disappointing performance and fuel economy.

When Cadillac introduces a new, third-generation, 2014 CTS later this year, they won’t repeat past errors. A 420-horsepower (at 5,750 rpm), twin-turbocharged 3.6-liter V6 will be available. The new engine will produce 430 pound-feet of torque at 3,500 rpm. When mated to a new eight-speed automatic capable of skipping gears, GM forecasts it will earn EPA ratings of 17 mpg city, 25 highway.

A variant of the new engine will also be offered in the Cadillac XTS, where it is also badly needed. Because the XTS has a transverse powertrain, I suspect that the new engine will have to be limited to about 365 horsepower and 350 pound-feet of torque in that application. This is the case with the EcoBoost V6 in the competing Lincoln MKS, which uses a related transmission.