How to Clean Up the Dirtiest Vehicles on the Road

When it comes to cleaning up automotive emissions, Tesla gets all the love. The upstart automaker garners the headlines and praise for making electric driving not just feasible, but sexy. That’s important, but all the attention on innovations for personal cars misses one critical fact: The cars most people drive each day are already among the most fuel-efficient vehicles on the road. Meanwhile, the real emissions offenders—buses, delivery trucks, dump trucks, long-haul trucks—have managed to avoid much improvement over the years.

“The thing about modern cars is, they’re so incredibly clean already, that it’s hard to make them any better,” says automotive engineer and entrepreneur Ian Wright, who co-founded Tesla but left in 2005 to focus more on the dirtiest vehicles.