Honda Motor slashed its annual profit and global sales outlook to a four-year low, citing a firmer yen and bleak business in both India and its main market of North America, even as it unveiled plans to buy back $915 million shares. The dour outlook comes at a time when Honda is struggling to shore up its automobile operations, with its profitability down more than half in the past two years due to a series of quality-related issues constraining its financial firepower to invest in new vehicle tech.