Don't think you've been watching how we operate, not to mention you're obviously not used to the delays we get in ATL (although PHL should be similar when they get really jacked up).
For example, this morning in MCO we cranked one engine, taxied from the gate, were told to follow one of your 737's, turned the corner behind you on Echo, started cranking the other one, had it all done by the time we turned the corner at the end for 35L, you guys were rolling, we were told to line up and wait, took off 90 seconds later. Probably saved 50 pounds of fuel.
Multiply that times 6 legs per day per aircraft average, 300 pounds per aircraft times 150 airplanes (rough numbers for easy math) is 45,000 pounds per day, or 6,750 gallons at an average price of $2.35 per gal is $15,862.50 times 30 days per month is $475,875 savings per month. The actual number from the company is considerably higher as some times you can save 200-300 pounds in ATL and PHL and even more with ground holds.
We don't take delays because of our single engine taxi and save approximately $500k+ a month in fuel, or about $6 Million a year. Multiply that times your fleet size and that fuel savings jumps close to $30 Million a year.
Scuttlebutt is that our single engine taxi procedure is the first change you guys might make to save some $$$. Enjoy!