On May 19, 1998, at 1445 central daylight time, a Stemme S10V, N97MT, piloted by commercial pilot, sustained substantial damage when it impacted the terrain during an off-airport landing. The commercial pilot was unable to transition the motor glider from soaring mode to powered flight mode. Visual meteorological conditions prevailed at the time of the accident. The 14 CFR Part 91 pleasure flight was not operating on a flight plan. The pilot and one passenger reported no injuries. The local flight departed Sheboygan County Memorial Airport, Sheboygan, Wisconsin, at 1245. According to the pilot's written statement, he was trying to locate sustaining lift over the Kettle Moraine front hills when it became evident that the aircraft had insufficient glide altitude to make the predetermined landing area. The pilot indicated that this decision was made around 1000 feet above ground level (agl). The pilot initiated the engine restart sequence, but when completed noticed that throttle movements did not produce power changes. The pilot stated he checked both fuel selectors for correct position, checked that the fuel pump & emergency fuel pump were on, and finally reactivated the nose cone opening lever. The pilot said he picked a field for an off-airport landing and initiated a normal gliding approach to the field. The pilot stated in a telephone conversation, with the Investigator-In-Charge (IIC), "Between 100 and 150 feet of the off-field landing site I decided to turn into the wind, which was at a 45-degree crosswind, and the left wing tip contacted the ground in a 20-degree bank." The pilot stated that the aircraft has a 75.5' wing span. According to a written statement from an inspector with the Federal Aviation Administration (FAA), the pilot stated that he didn't believe the engine was developing power at the time of the accident. Furthermore the pilot stated that, "he attempted to alter his landing course at too low of an altitude which resulted in the left wing contacting the ground and the subsequent aircraft breakup." The pilot also made the statement that 1000' agl was probably too low of an altitude to safely initiate the engine restart. Post accident investigation showed that there was usable fuel in both of the wing tanks. The engine and the drive train were undamaged from the accident. Both propeller blades were removed to facilitate a test run of the engine. The test run showed that the engine started, without hesitation, and throttle response was determined to be normal. Engine controls and indications appeared to be in the normal operation limits. No other discrepancies were found.