Toyota and Ford have ended a partnership to jointly develop gas-electric hybrid systems for trucks and sport utility vehicles, the automakers said Tuesday. \"We know what it takes to build world-class hybrids, and we now will build and leverage that expertise in-house,\" said Raj Nair, Ford\'s chief of global product development. \"By continuing to develop a rear-wheel-drive hybrid system on our own, we can extend our advanced hybrid technologies to new vehicle segments and deliver even better fuel economy across our lineup.\" Ford -- the second-largest US automaker -- said it is hiring more than 200 new electrification engineers and expanding its research facilities to speed development. \"Toyota and Ford continue to evaluate the feasibility of working together on next-generation standards for telematics and will consider other areas for future collaboration as well,\" Toyota said in a separate statement. The Japanese automaker said its commitment to hybrid technology is \"unwavering\" and that it remains on track to offer 18 new or redesigned hybrid models globally by the end of 2015. Toyota has already sold over two million hybrid vehicles in the United States -- 70 percent of the nation\'s hybrid sales -- and over five million hybrids worldwide. It estimates that those vehicles have saved their owners more than 3 billion gallons (11.3 billion liters) of gasoline. Ford said it has invested $355 million within the past year to design, engineer and manufacture key components for its electrified vehicles. It plans to invest another $50 million to double its battery testing capabilities and speed electrified vehicle development by as much as 25 percent. Ford said its second-quarter hybrid sales soared a whopping 517 percent from the first quarter of 2012 to a record 24,217 vehicles. Its share of the US electrified market grew 12 points to nearly 16 percent of the US market, Ford said.