[Overdriven]

The smallest co2 being made now is 5lb, they stopped making 2.5lb as they are useless. IMO 10lb is the minimum co2 size, as they can make a decent stream so you don't have to be too close, 5-10ft away would still be the max distance depending on wind, type of fire, where it is, etc. CO2 is great for real car engine fire or any fire that can't be attacked directly and is a corner not easily reached. But they are also expensive, about $225 for a 10lb, which isn't the most portable thing in the world. Get a decent 5lb ABC (don't cheap out with a 2.5) stick it in the trunk, under the sink, in the garage, etc and be done with it.

I find it funny when computer geeks want a Halatron fire extinguisher (halon replacement) for their computer rooms. They are more expensive than CO2 and you still have to be there to use it, if you're not, it's just a nice decoration. I always tell them, get an automatic fire ext ($2k and up) or don't waste your money on anything more than ABC. The computer is going to be toast anyway if it caught fire and you didn't get to it real quick. Just take a look at that mugen mrx4 fire. They got to it in time, but didn't have an ext, all it took was another min to destroy the rest of the car.