On July 24, 2000, at 1144 central daylight time, a Cessna 210N, N5525A, operated by Teledyne Continental Motors as an experimental airplane for research and development, was substantially damaged during a forced landing on Illinois Route 145, approximately 12 miles south of Harrisburg, Illinois. The private pilot reported a loss of engine power. Visual meteorological conditions prevailed at the time of the accident. The 14 CFR Part 91 business flight was not operating on a flight plan. The pilot reported no injuries. The flight originated from the Mobile Downtown Airport, Mobile, Alabama, at 0845, en route to the Central Illinois Regional Airport, Bloomington, Illinois. The pilot reported during a telephone interview that he was one of three aircraft en route to Oshkosh, Wisconsin to "work" the Experimental Aircraft Association's annual airshow. He stated that the aircraft's power setting was 20-22 inches of manifold pressure, or "wide open throttle", at 2,450 rpm, while en route at 6,500 feet msl. The pilot also stated that there was a 1/2 tank of fuel in each tank. In a written statement, the pilot reported, "...At approximately 1140 CSDT and 25 nm NNE of Paducah, KY, the engine instantly began running violently rough and the RPM began dropping. I immediately turned towards Harrisburg, the closest airport, and 15 nm away. I established my airspeed at 85 knots. I then began to troubleshoot the problem by selecting AB channels (the equivalent of R and L mag check) and cycling the FADEC system. Aux boost pump was selected to high for approximately 20-30 seconds with no noticeable change to the engine performance. The engine was still running roughly at 1100-1200 RPM. Throttle position was changed, also with no appreciable difference." "At this time it was apparent that I would not make Harrisburg, so I lined the aircraft up over the closest highway (Illinois hwy 145) approximately 2 miles to my right. This road had but one lone straight stretch, of which I believed I could make. The aircraft's descent rate at 85 knots was 700 fpm. As I approached the highway it became apparent that I would not make the straight stretch of highway, but would be very close. The approach end of this stretch of highway was a hill with trees on both sides, approximately 8-10 ft off either side, a ditch on both sides and had a powerline at the hill's crest. Because of the hill, I was unable to determine if a car was on the highway so I gave right away as best I could without getting into the trees. Since it was obvious that this was not going to be a "normal" landing on the straight portion of the highway, I left the gear up, thinking it safer with the trees and ditches. As I approached touchdown, a car breached the hill and I banked more right to ensure the cars safety and the right wing began hitting the trees. I then dumped the aircraft, striking pavement first, and slid straight down the roadside in the grass coming to a stop approximately 50-75 yards from touchdown." "This location was 1 hour and 15 minutes (GPS) from the scheduled Bloomington fuel stop. Fuel on board was indicated at slightly over half tank on the left tank and slightly over 1/4 tank in the right which was consistent with the estimated and planned 15 gph fuel burn. I was 5 minutes away from selecting the left tank for the 4th and final hour flight duration. Estimated fuel onboard at arrival at Bloomington was to have been approximately 12-15 gallons a side." "...A check of the FADEC systems with a computer showed no noted problems. ...performed a fuel feed check at the fuel distribution valve with less than desirable feed from the right tank and positive feed from the left tank. ...another check was performed, this time with the wings leveled and a positive feed was observed..." The pilot reported 90 gallons of fuel on board at the last departure point. A Condition and Operability Report by Teledyne Continental Motors, included in this report, describes the off site testing of the engine. A report states that a five-gallon can of 100LL aviation gasoline was strapped to the top of the fuselage. A number 8 AN line was connected to the right hand fuel feed line at the wing root and tygon type flexible tubing was connected to the right fuel return line. The slave fuel supply line was filled with fuel, by siphon action, to simulate gravity feed from the right wing tank. Steady state operation between 700 and 800 rpm with no FADEC system faults was recorded for 52 seconds. A slow acceleration from 850 to 1,150 rpm was performed with a total recording time of 70 seconds. No abnormal FADEC system operations were detected. A check of A channel and B channel operations was conducted at approximately 750 rpm for 27 seconds. RPM drop was equal in each channel and no abnormal cylinder operation was detected in A channel, B channel or both conditions. At a steady state operation of 1,000 rpm, a total of 155 seconds of data was recorded. FADEC system parameters indicated normal function.