Last time, we introduced you to the basics of vehicle emissions and fuel-economy certification and the complex processes involved. In Part II, we'll explain the certification tests themselves, the final certification process, and the resources -- people and facilities -- required for every U.S.-market automaker to get it all done.

The Tests
Once the worst-case emissions-performance vehicles from each test group have been established, each is taken through a standard battery of certification tests. (A test group is a set of vehicles with essentially the same engine and emissions control system.) The EPA's original rules required just two standardized tests: the 42-minute Federal Test Procedure (FTP), which simulates stop-and-go city driving, and a 13-minute highway test that approximates gentle highway driving up to 60 mph.

New requirements in the mid-1990s added three more: a US06, hard-acceleration, high-speed, aggressive highway test with speeds up to 80 mph; an air-conditioning-on SC03 cycle that mixes city and highway driving at high ambient temperature and high solar load; and a Cold Test that is essentially the first 8.3 minutes of the FTP done at either 20 degrees or 50 degrees F, depending on whether it's for EPA or CARB.

"That's the tailpipe side of the equation," says Todd Fagerman, Ford's emissions certification manager. "There's also the evaporative emissions side, which is looking at emissions that escape from places other than the tailpipe. There are several tests for that -- a two-day test, a three-day test, a running-loss test at elevated temperatures, tests that measure vapors that escape during refueling, and "spit-back" tests to make sure fuel doesn't spit back during refueling.

"The two- and three-day tests actually take from five to seven days because several days of preparation lead up to them. There's a series of preconditioning events where the evaporative canisters are loaded and purged and the vehicle is driven and subjected to temperatures and conditions it would experience in the real world to get it into a representative state. Then it's parked in what's called a shed for the designated length of time and cycled through temperature variations to simulate what happens in a parking lot -- cool in the morning, heating up through the day, cooling down overnight -- and through the same cycle the next day. The shed captures any vapors that escape, which are then analyzed."

"The federal and California tests are essentially the same," adds Dave Garrett, GM's director of emissions compliance and certification. "There are some slight, subtle differences in how you conduct them -- the fuel you use or the temperature at which you run -- but the test cycles are generally the same, though the standards may be different. It's a complicated alphabet soup of standards. There are, in general, corresponding California standards to those for the EPA, but they don't all mix and match very well. For federal vehicles, the standard is Bin 5. The equivalent standard in California is LEV [Low-Emissions Vehicle] II. There is also ULEV II, which is ultra-low emissions vehicle, SULEV II, super low emissions vehicle, and ZEV, zero emissions vehicle."