PACCAR Inc's first-quarter results reveal an 8.9% revenue decline, falling short of estimates by 0.9%, causing shares to drop 6.1%. Despite this, the company generated $6.8 billion in revenue and reported earnings per share of $1.15, above analysts' expectations. The company is planning significant capital investments and R&D expenses while addressing increasing inventory levels and a year-over-year earnings decrease of 21.2%. PACCAR remains optimistic about future demand, having delivered 33,000 trucks in the quarter.