Might work for a small fire, but I think you would have to have a REALLY high flow regulator for that to be effective for a large fire, not to mention the difficulty of getting close enough to be effective. One of those long blow gun nozzles might be helpful to avoid removing the hair from your arms and face...
Another thought regarding repurposed Powertanks, esp. if they are accessable from the driver seat- plumb in a line to the engine compartment, redneck fire suppression system. I've used a similar method(using actual fire extinguishers, however) in demolition derby cars with good sucess.
ive had to put out a car fire. those fancy 2.5 pound chrome extinuishers are about useless. mid 90's camaro tpi had a small fire in the back under the distributor . had about 5 seconds of spray just barely covered it . get the biggest extinuisher you can. yes something is better then nothing but false hope is even more crushing. remember the powder packs so bang that thing a few times to loosen it up. CO2 should work too but i believe commercial tanks are bottom drawn in liquid to get the flow and cold temps. there are a few commercial systems for racing safety but those start in the hundreds of dollars.