The oil-burning Cadillac STS has been thought up to tackle the increasing diesel-powered segment in the States, as well as offering a viable alternative to petrol STS models in world markets.

No, this isn't a half clapped-out Cadillac STS. Infact, it's a new diesel version of the STS undergoing testing on European soil. The oil-burning STS is being tested on the European continent due to its abundance of engineers with experience of diesel technology and has been thought up to tackle the increasing diesel-powered segment in the States, as well as to offer a viable alternative to petrol STS models in world markets.

Our source suggests that the 1.9-litre turbodiesel unit used in the BLS is likely not to make the Stateside STS line-up, with the introduction of Opel's 184 hp 3.0-litre V6 being the preferred powertrain. However, capable of 56 mpg on the combined cycle, the 1.9-litre unit may make a late range entry should the V6 take initial preference. Opel's 3.0 V6 as featured in the Vectra range provides a 41 mpg combined figure.

While the transplanting of the GM stablemate's 3.0 V6 into the STS is likely, the in-house engineered unit of choice for the firm may very well be a 2.9-litre V6 turbodiesel, premiered at this year's Geneva Motor Show. It was however maintained in an announcement at the show that the 250 hp unit was likely to be sold only in European-spec Cadillacs, taking on Europe's finest with the all-new engine.

Speculation is sure to be rife ahead of the oil-burning STS' debut, so stay with us for further details.

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Cadillac STS Diesel Spotted Undergoing Testing