A while back, the Seattle P-I ran a story about how Seattle’s new diesel-electric hybrid buses weren’t as fuel-efficient as advertised.  Our response was basically a shrug.  The chief benefit of hybrid buses, we argued—particularly through the downtown bus tunnel, where many of Seattle’s hybrids are routed—is that they reducing pollution, not that they burn less petroleum.

Except now, a study from the University of Connecticut (via this post at Green Car Congress) found that GM’s hybrid buses really may not actually reduce pollution coming from the buses’ tailpipes.  In fact, driving identical routes, the standard diesel buses seemed to emit a bit less particulate matter (a particularly nasty problem for diesel engines) than the hybrid buses.

This, of course, comes as a surprise—the air in Seattle’s bus tunnel’s has seemed surprisingly pleasant to me, even after the city switched from all-electric to hybrid buses through the tunnel.  So I’m not sure what to make of it.  But still, there’s probably a lesson to be learned here:  you have to be really careful not to be sucked into the hype surrounding new technologies. Sometimes the benefits don’t pan out until the technology is refined; and other times, the benefits may never materialize at all.