UPDATE: The Toyota-BMW team-up has just been confirmed as the two companies have signed a mid- to long-term agreement to develop next-generation lithium-ion batteries with the option to expand the partnership into additional areas as well. In addition, BMW has announced that it will supply Toyota with 1.6- and 2.0-liter diesel engines beginning 2014. These engines, however, will be used for Toyota products solely for the European market.

The Japan Times has reported that Toyota and BMW are reportedly beginning discussions on swapping their green technologies. In this agreement, it's believed that Toyota would open up its gasoline-electric hybrid technology to BMW, while the German automaker will provide diesel engines for Toyotas.

The BMW/Toyota team-up is all to save money on "core technologies". For BMW, this would mean a better stronghold in the US market where gasoline-electric hybrids are strong, while Toyota's interest would be to improve its diesel position in Europe.

There is still no deal in place, but one can only imagine seeing a Lexus powered by a diesel BMW engine or a BMW with a Toyota/Lexus hybrid engine.