It can be done but I would be very concerned about tube elements shorting when the car hits bumps, etc. As absurd as it sounds, I considered a tube amp for a bicycle
. I rejected the idea when I thought of the shorting potential. The bicycle stereo I later constructed with a chip amp.
Next issue is supplying high tension with a 12 volt DC electrical system. You could either do it two ways:
-A boost type switching power supply. This would be the most efficient but may not sound the best.
-This method is inefficient, expensive, and sounds like it it is beyond the scope of your electronics knowledge. The system would start with a square wave oscillator at 60Hz. A low q, high-order active band filter with resonance at 60Hz will then filter the harmonics of the square wave to yield a clean 60Hz sine wave. This is fed to a solid state power amplifier. The power amplifier feeds the primary of a 12 volt step up transformer.
I would not trust those car AC power adapters as they are cheap and harmonic filtering in them is poor. I do not think they like highly reactive loads either.
What do you want to do with your car anyways?
-Ice cream is irresistible.
-Spaghetti and salt is irinductable.
-Artichokes are ircapacitable.