The heat exchanger your are referring to on a truck is not used directly for power generation, but to transfer heat from the exhaust to the intake, thereby changing the power cycle.
Radiant heat is actually one of the better ideas that I've seen, but depends on the ability of the trucks to absorb the radiant energy. Most heavy-haul trucks I've seen are usually a bright yellow. But a DIRTY truck might be a better black body. You could potentially use radiant heat to heat...
