Ford Motor Co. knowingly launched two low-priced, fuel-efficient cars with defective transmissions and continued selling the troubled Focus and Fiesta despite thousands of complaints and an avalanche of repairs, a Free Press investigation found.

The cars, many of which randomly lose power on freeways and have unexpectedly bolted into intersections, were put on sale in 2010-11 as the nation emerged from the Great Recession.

At least 1.5 million remain on the road and continue to torment their owners — and Ford.

The automaker pushed past company lawyers’ early safety questions and a veteran development engineer’s warning that the cars weren’t roadworthy, internal emails and documents show. Ford then declined, after the depth of the problem was obvious, to make an expensive change in the transmission technology.