Don’t ask for plastic, that’s for sure. It’s what got the first of many normal Americans arrested by the Green Police in the spoofy Superbowl ad for the 2010 Audio A3 TDI. Its special green feature: clean diesel power.

It actually took a long time to get to the point about the greeniness of diesel in the ad. But it was a fun wait, as the Audi Green Police systematically bring the Tea Party’s worst nightmare to life –  hordes of socialist green police arresting unwary Americans in the act of not-being green. Was easy to picture Al Gore directing this gem of a commercial.

First a guy gets knocked down and cuffed for asking for a plastic grocery bag, “Ya picked the wrong day to mess with the ecosystem, plastic boy!” growls the burly green cop.

Then backed by a 1980′s style rock ballad extolling the virtues of the green, you see shots of:

• police discovering a battery that was in the trash instead of being recycled
• a helicopter putting a spotlight on a homeowner committing a “compost infraction” for putting his orange peel in the garbage disposal
• the arrest of a home owner for using incandescent light bulbs
• a couple being harassed for heating their hot tub to 105 degrees, and
• a cop scolding two teenagers as he empties their plastic water bottles.

Then, finally, in a traffic roadblock to check on all sorts of anti-green driving, the Green Police let the driver of the Audi A3 TDI out of the backup and scoot him on his way because he’s driving a clean diesel car. “You’re good to go, sir!”

Consider vehicles that run on compressed natural gas (CNG).

In the right circumstances, companies not only get some credits for reducing their carbon footprint, but CNG-powered vehicles have the range to cover most business needs in a day and can be cost competitive with gasoline and diesel.

This is not a pie-in-the-sky environmentalist pipe dream. CNG vehicles are proven alternatives to petroleum-powered vehicles.

That’s why United Parcel Service (UPS) just expanded its already prodigious fleet of alternative fuel vehicles (AFVs) that run on CNG. The national delivery company just added:

• 140 CNG trucks to its fleet in Denver, CO
• 18 CNG trucks to its San Ramon, CA, fleet
• 16 CNG trucks to the Fresno, CA fleet
• 59 CNG vehicles to its West Los Angeles fleet, and
• 12 CNG-powered trucks to its fleet in Ontario, Canada.

These trucks join more than 900 CNG vehicles in use by UPS worldwide. The trucks look identical to the standard brown UPS vehicle.

UPS does gain credits for cutting greenhouse gas (GHG) emissions by switching to cleaner burning CNG. But that’s not the driving factor.

CNG makes economic sense right now, and UPS has the experience to prove it. CNG is a “sustainable technology for UPS’s fleet because natural gas is cost effective, clean-burning and abundant,” UPS senior vice president Bob Stoffel said in a statement announcing the fleet expansion.

The use of CNG vehicles makes most sense for companies that can centrally fuel their fleets.