Subaru were being a bit ballsy to try that as they only won in one category whereas BMW won in four categories and overall in 2006. In 2007 they upped that to six categories and the overall win.
2006 Winners
Best New Engine: Volkswagen 1.4-litre TSI Twincharger
Best Fuel Economy: Toyota 1.5-litre Hybrid Synergy Drive
Best Performance Engine: BMW 5-litre V10
Sub 1-litre: Honda 1-litre IMA
1-litre to 1.4-litre: Volkswagen 1.4-litre TSI Twincharger
1.4-litre to 1.8-litre: Toyota 1.5-litre Hybrid Synergy Drive
1.8-litre to 2-litre: Volkswagen 2-litre FSI Turbo
2-litre to 2.5-litre: Subaru 2.5-litre Turbo
2.5-litre to 3-litre: BMW 3-litre Twin Turbo Diesel
3-litre to 4-litre: BMW M 3.2-litre
Above 4-litre: BMW 5-litre V10
International Engine of the Year 2005: BMW 5-litre V10
2007 Winners
Best New Engine: BMW 3-litre Twin Turbo
Best Fuel Economy: Toyota 1.5-litre Hybrid Synergy Drive
Best Performance Engine: BMW 5-litre V10
Sub 1-litre: Toyota 1-litre
1-litre to 1.4-litre: Volkswagen 1.4-litre TSI Twincharger
1.4-litre to 1.8-litre: BMW-PSA 1.6-litre Turbo
1.8-litre to 2-litre: Volkswagen 2-litre FSI Turbo
2-litre to 2.5-litre: BMW 2.5-litre
2.5-litre to 3-litre: BMW 3-litre Twin Turbo
3-litre to 4-litre: Porsche 3.6-litre Turbo
Above 4-litre: BMW 5-litre V10
International Engine of the Year 2005: BMW 3-litre Twin Turbo
P.S. Has anyone else noticed that SUBARU spelled backwards is "U-R-A-BUS"