After four years of rumors about a Lexus LS powered by a hydrogen fuel cell, the chief engineer of the flagship sedan says the carmaker's working on even more options. Toshio Asahi told Australia's GoAutothat three alternative powertrains — plug-in hybrid, full electric, and hydrogen — are "all on the table" for consideration. Asahi wouldn't give any timeframes, but whenever they arrive, additional drive options would fill out the LS range to better contend with the Germans.

Years of reports predicted this fifth-generation LS would get hydrogen power. A Motoring article at the end of 2014 forecast a fuel cell LS to arrive by 2017. In 2015 Japan's Nikkei newspaper reported that Lexus was considering a fuel cell option to arrive in 2020, around the time of the Tokyo Olympics. Later that year, at the Tokyo Motor Show, Lexus showed off the LF-FC concept, powered by a cell and stack arranged for "optimum front-rear weight distribution for a sporty saloon." GoAuto said that during that show, a Lexus executive said an FCEV powertrain would end up in production "sooner than you think." The following year, Autocar reported we'd see a production version of the LF-FC "on sale before 2020" as a replacement for the LS, and last year, Lexus trademarked the name "LF-FC Concept."

The intel gets murkier regarding plug-in hybrid and full electric versions. We now know Lexus is working on a more powerful hybrid system. The current hybrid produces a total system 354 horsepower and 258 pound-feet of torque using the same 3.5-liter V6 in the standard car as a base, though the standard car adds two turbos for 415 hp and 442 lb-ft. The coming hybrid will likely use the twin-turbo setup and could achieve two important ends: Smoothing out noted issues of powertrain refinement, and at least matching the power specs of Mercedes-Benz and BMW flagship plug-in hybrids. That hybrid LS would still miss out on the all-electric driving of its rivals. If there really is an LF-FC coming in the next two years, it would seem a perfect time to retire the conventional hybrid and introduce a plug-in version embodying the velvet sophistication Lexus is known for.

The battery electric LS is a big question mark outside of Lexus HQ. Last year Toyota announced a breakthrough in solid state battery technology, the carmaker announcing it wanted such batteries on the market by 2022. The technology won't be cheap, making an LS the perfect car to launch it, and compete with Mercedes' electric EQ S sedan slated to arrive in 2020.