I have a 2005 Saab 93 2.0T. When I press on the gas white smoke comes out. Starts up right away. Turbo is good. I had a code P0300 like 4 days ago but it went away. No check engine light. Even with scanning it.
If it's not the usual water vapor when air temp is low then white-ish smoke would mean coolant is burning from a leaking head gasket. Check the level in the recovery tank daily, it should be about halfway when the engine is cold. It uses DexCool which is orange-pink, don't use other coolant. If level drops, it's being burned in the cylinders which might also result in a misfire code P0300.