DETROIT (AP) — U.S. new vehicle sales fell slightly in the third quarter, even with improvement in September. But there are warning signs consumers’ appetite for expensive new cars, trucks and SUVs may be waning. Edmunds.com says sales fell 0.9% from July through September. Multiple companies reported sales declines for the quarter on Monday, with General Motors a notable exception. However, many said sales rose in September as shortages of computer chips and other parts started to ease and auto factories were able to produce more. That increased vehicle supplies. But any monthly gain may be short lived due to high prices and rising interest rates.