Remote laser sensors placed on both sides of the road quickly detect four types of exhaust emissions. A camera also grabs a picture of the car and license tag.
With more cars on the road and inspection fees going up, the remote-sensing vans may ease the inspection process without involving drivers.
"I can do three to four cars a second, and it does not impede traffic at all," says MD Lasertech technician James De Shazo.
The $200,000 vans will not replace inspection stations. They will be used to measure the effectiveness of the state's emissions program.