WASHINGTON—President Donald Trump directed federal officials to expand Americans’ access to automobile parts and allow independent repairs with the signing of a presidential memorandum titled “Lowering the Cost of Living by Promoting the Freedom to Fix” during a White House ceremony on Monday. “We have a big ruling that we’re just issuing now,” Trump said while seated behind the Resolute Desk in the Oval Office. “I think it’s very important to lower the price of your car.” The president emphasized the cost-savings for Americans who can repair their vehicles and choose parts manufactured by third parties....