On a scorching summer day during the 1979 oil crisis, Alex Severinsky, a Soviet refugee, sat for 45 minutes in a sweltering Oldsmobile Cutlass, waiting for the chance to buy gasoline in Dallas. "I'm thinking to myself, in Moscow I'd wait in line in temperatures that were minus 20 to 30 degrees Centigrade for food. Here I'm doing the same thing, not for food but for gasoline!"

With an inventive streak and a Russian Ph.D. in electrical engineering, Severinsky, then 34, began working on concepts to improve fuel efficiency. His research led to a patented breakthrough for a hybrid-electric car that has now put him at odds with Toyota Motor, the world's largest maker of hybrid vehicles. He has won several rounds in the courts, but Toyota is contesting the amount it was ordered to pay in royalties. If his tiny Florida company, Paice LLC, prevails at an International Trade Commission hearing in July -- a long shot -- Toyota could be banned from importing its newest hybrids, including the popular Prius.

The patent dispute is just another headache for recall-plagued Toyota and, potentially, for the whole car industry. Toyota and other carmakers are expected to sell 2.6 million hybrids a year by 2016. A 2009 study by Griffith Hack, an Australian intellectual property law firm, found that Paice owns four of the ten most dominant hybrid patents. Paice recently sued Ford Motor on similar charges; negotiations continue.

Severinsky's bright idea was to run the electric motor on a high voltage--say, 40 times the 14 volts that is standard for the electrical system in a gasoline car with a 12-volt battery. With more volts you don't need as many amps, which means the system doesn't run as hot and less energy is wasted. Now, engineers have been making this tradeoff between volts and amps since the 19th century. Was it a stroke of genius to raise the volts in a car's electrical system? Evidently the Patent Office thought so, at least when Severinsky, now a U.S. citizen, presented it as the ideal balance between performance and cost. He got a patent in 1994 and built a prototype in 1999. With $15 million in financial backing from the Abell Foundation in Baltimore, Severinsky spent the next five years trying to license his technology to U.S. and foreign carmakers, including Toyota, which had begun selling the Prius in the U.S. in 2000.

Their legal fight began in 2004, shortly after Toyota introduced its second-generation Prius, which was vastly improved in both performance and efficiency. In a 2004 corporate report Toyota said the key to the improvements was its decision to switch to a high-voltage system.

Paice sued, and in 2005 a federal judge in Texas ruled that Toyota had infringed one of Paice's patents. His ruling was upheld by an appellate court in 2007. Toyota then appealed to the U.S. Supreme Court, which refused to review the case. Toyota has paid $5 million in damages and a small fraction of the court-ordered license fee of $98 a car while it challenges future royalties.

With its main patent set to expire in 2012, Paice is asking the ITC to protect it from unfair competition by banning Toyota hybrids. But without any other customers, Paice has an uphill fight there. Severinsky's best shot at wealth is the $98 fee.