Hooded in Logan County, Illinois

I had actually put most of the details out of my mind, until a friend asked me a few months back if I had ever had a sighting. It was October '04 between 9-9:30pm, heading south about 3/4 of the way to Springfield Il. after passing the interchange to go to Lincoln, not sure which county. There weren't many cars on the road. We were in the left lane, I was the passenger. At the very far edge of the high beams I saw what looked like one of those big black 50 gallon lawn bags sitting with a bunch of garbage right off the side of the road between where the pavement meets the grass. It looked like someone had dumped trash... I was wrong! Grant you this all took place in like 8-9 seconds. As we got closer I saw the garbage was fast food bags and the black garbage bag had arms and a head! When we were maybe 5-6 car lengths away it swung its arms out in front of it and shot straight up, taking a small step backwards. My friend and I both said 'what the hell is that?' As he slowed down a little. In the split seconds it was full on in the head lights standing I saw a medium build, not massive at all, but thick, hair was 4-6" and flat black in color with just a little bluish silver reflection from the headlights and the face was a lighter shade than the hair like charcoal grey, I don't recall seeing breasts and the hair seemed thinner and shorter on its front. Facial features at that speed were impossible to make out, but its chin seemed to jut out from where the collar bone area would be on a human. My friend owned a Mitsubishi Montero at that time. It rode about as high as the smaller big pick up trucks do. I'm 6'4" and I had to step up slightly to get into the seat, and as we passed it close up, in the windshield and out the drivers side window its waist was as high as the top of the hood, probably 4 1/2 feet, and the rest was at least that much. My friend asked me; "Dude was that Bigfoot?!" at the same second I yelled "That was Bigfoot!." Funny I have read countless books on the subject from the time I was in grade school, and let me tell you... All the information in the world beforehand does not prepare you for a sighting.