Whispers out of GM suggest the company is actively considering fitting its smooth, innovative new 4.5L Duramax V-8 turbodiesel into the engine bay of the Cadillac CTS. Fitting the engine is relatively straightforward, say sources, as long as Cadillac uses the raised hood from the CTS-v.


While it was initially expected the engine would serve in SUVs and light-duty pickups, GM engineers have long pointed out that the dual overhead cam, four-valve diesel V-8 will fit in the same space as a small-block gasoline V-8. They say the Duramax has been specifically designed for "a wide variety of vehicle applications." That obviously includes passenger cars.


GM says the 4.5L Duramax, which features aluminum cylinder heads with integrated manifolding and a variable-vane turbocharger mounted in the vee, is capable of delivering more than 310 hp and in excess of 520 lb-ft of torque. It also claims the engine meets the tough 2010 emissions standards, making it legal in all 50 states.


Why do it? While the CTS is due to get a 2.9L V-6 diesel in Europe, the 4.5L diesel V-8 would most likely be seen as a way of filling the obvious gap between the 304-hp direct-injection V-6 of the regular CTS and the 556-hp supercharged V-8 of the CTS-v here in the U.S. -- especially now that the Ultra V-8 engine program (which was to have provided a replacement for the aging Northstar) has been canned. In the CTS, the Duramax V-8 could easily deliver comparable performance to the Ultra, with 20-25%-better mileage.


A diesel CTS for the U.S. would be a risk, but the downside for GM is in fact minimal. The engine already exists, as does the transmission capable of handling the torque, so there's little incremental investment required and therefore fewer sales needed to make the business case. The Duramax play also makes sense in light of the proposed CAFE regulations mandating 35 mpg average by 2020.


American consumers are rightly wary of diesels, but moves by Mercedes-Benz, BMW, and Audi to bring 50-state-legal diesel cars to the U.S. will help transform the oil-burner's image here over the next few years. And it certainly won't hurt Cadillac's image to be seen offering the same sort of technology as Europe's blue-chip luxury brands.
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