In a past career (long ago), I was a steam engineer (power plant operator) at Misericordia hospital in Edmonton. One thing I did frequently (about 3 times a week) was put out car fires in the parking lot, almost always due to people using cheap, under-rated extension cords for their block heaters (or a splitter to battery heaters and oil heaters). One thing I learned by hard experience was that any extinguisher that was gas based (e.g. CO2) would immediately put out the fire under the hood, and as as soon as the CO2 dissipated, the fire would reignite from the stored heat in the engine block. I would never trust anything but the good old ABC extinguisher, complete with all of the mess -- those things put out the fire and kept it out.
So, not a plus vote from me,