You can lead a horse to trendy water all you want, but you can’t make it drink from an unsafe well. That’s the message out of Toyota, whose officials have made it a no-go to put lithium-ion batteries in the next generation of the wildly popular hybrid Prius.

Nickel hydride batteries, the current power choice, will continue to be the standard, despite their lower fuel efficiency than lithium-ion. The latter, however, have caused all kinds of trouble in laptops in the past year.

Toyota, ever looking to increase fuel efficiency—even in its hybrids—will work with existing technology to refine the fuel injection process even more to increase gas mileage. One method for doing that is incorporating a plug-in system, which has the potential to greatly increase efficiency.