Today’s hefty automotive cooling systems, which can barely keep up with the heat produced by our car engines, may be inadequate for cooling the more demanding hybrid and fuel-cell vehicles of tomorrow. For a boost in cooling power, Stephen Choi and his team at Argonne National Laboratory have added nanometer-size copper particles and carbon nanotubes to radiator fluids such as ethylene glycol. Because the solid particles conduct heat a thousand times better than most liquids, researchers have been dreaming of such liquid-solid mixtures for decades. But it is only recently that they’ve been able to create particles small enough that they don’t settle out of the fluid or abrade engine blocks. So far these nanofluids have demonstrated more than double the cooling capacity of typical coolants; that could translate into smaller, lighter cooling systems and better gas mileage. Argonne is partnering with several companies to develop a cheap means of producing the nanoparticles and hopes to bring nanofluids to market within five years.