Sales of Class 8 trucks rose 39.7% in September compared to the same month last year, according to numbers compiled by Ward's Communications. The figures indicate that fleets bought heavy-duty trucks to avoid the October 1 EPA deadline for diesel engines with reduced emissions. Ward's reports that 13,502 Class 8 trucks were sold last month. Class 8 sales in August 2001 totaled 9,667. Peterbilt and Kenworth, which both offered a variety of incentives to fleets that purchased trucks with the new engines, respectively sold 1,953 and 1,690 trucks with the old engines. Peterbilt sold 1,128 last September, while Kenworth sold 686. International, which offered cash incentives for trucks with post-October 1 engines, sold 2,309 with the old engines. It sold 1,408 Class 8 trucks last September. OEMs and analysts believe sales will now drop because fleets will attempt to delay purchasing trucks with the new engines as long as possible. That could mean the slump in demand will continue through mid-'03.