It may come as a shock to some of you, but the ol' internal combustion engine is far from efficient. In fact, most modern engines can't harness even 50 percent of the energy contained in petroleum, thanks to a sizable proportion of it being converted into heat rather than mechanical power.
Salvation may be on the way however, as German automakers Volkswagen and BMW are currently researching methods of recouping the energy contained in an engine's hot exhaust gasses. Thermoelectric generators (TEGs) are currently under evaluation by the two marques, and if the technology can be successfully applied to modern automotive powerplants the benefits will be manifold.
For starters, charging a battery using heat energy means the engine's alternator can be smaller, placing less drag on the crankshaft and thus freeing up more power for, oh I dunno, moving the car. The TEG also uses no moving parts and isn't overly complex in construction (the technology behind it has been around for decades), plus it's a means of getting free energy, energy that would've normally been pumped into the atmosphere.
Volkswagen is currently the leader in the automotive TEG stakes, with a prototype system that generates around 600W of electricity during highway driving - enough to meet 30 percent of the average car's electrical needs and improve fuel efficiency by over five percent.
BMW is slightly behind with its setup only generating 200W, however after subjecting the test mule to over 12,000 development kilometres, the system's robustness is without question.
While hybrids, electric and hydrogen cars undeniably form the future of motoring, it is still nice to see manufacturers haven't given up on the humble IC engine just yet. With more energy-saving/energy generating technology like thermoelectric generators on the way, hopefully we can stop worrying about the fuel we're burning and start enjoying the drive.