Good one. I actually have one of those convertible deals too. Mine says "Syngenta Seeds" on it and cost either $0 or tens of thousands, depending on your perspective.
On the subject of compressed air, I have a small 5 gallon compressor that I never use. I went to the welding shop and got a small nitrogen cylinder, regulator, and hose. I use that to fill tires & struts, and occasionally blow dust off things when I don't want to wait for/listen to the compressor. I've had it for five years and still never used up the first bottle. Now, if I was washing my engine like Gary a compressor would make more sense.
You'll probably also want a drip pan of some sort. Even if your engine doesn't leak, you'll get drips out of the crankcase vent tube which will make a mess on the floor. My wife found a very heavy baking pan at a thrift store that works great.