I wish I could sell a used car for my asking price.
Energy Matters:FLAT PLATE VS. EVACUATED TUBE SOLAR HOT WATER COLLECTORS/
These evacuated tubes are more efficient (and expensive) than a flat plate collector. If these tubes were inclined on a N-S axis at an angle dependent on the latitude; and if they were spaced further apart, each with a reflective sleeve that rotates to maintain an orientation to the Sun — then they would be still more efficient.