I have been meaning to add a little comment to this post for awhile.
I think I understand how fuel is used when to throttle is not applied... or while the car is coasting.
About a month ago, I was leaving my house in the morning, terribly late... and I had to run 10 miles south of my house, and then 25 miles north or my house... with no time (SHOULD HAVE!) to stop for gas... I was in a major hurrey, had to drive 35 miles and get to work in about 30 minutes. Well when I pulled out of my garage, the gas needle was in the red, and BARELY moved up.... but moved up nonetheless.
Anyways, to make a long story short, I was about one mile from work (and about 1/2 a mile from the gas station I planned on getting gas at) when I ran out of gas.... I was going about 50 mph when the fuel supply cut off.
I observed that the engine, when coasting (no throttle applied) (RPMs) was running at roughly 1500 (point being, ENGINE WAS RUNNING) with no gas applied. But when I would attempt to push the gas, the engine would sputter down, but then when I let off the gas, the engine ran again... with no fuel.
Just kind of proving that fuel isn't *needed* during coasting.
2006 E350 w/ 155k miles (Daily Driver)
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)