This investigation was opened based on a fleet complaint alleging delayed throttle response which could potentially lead to extended stopping distances and/or increase the risk of a crash.Autocar responded to ODI's Information Request (IR) letter and provided test data including its FMVSS 124 validation data.ODI reviewed Autocar's testing procedures and results with NHTSA's Office of Vehicle Safety Compliance and Office of Rule Making.The test procedure was acceptable as were the results.In an effort to further quantify the safety risk, ODI surveyed nine fleets operating the same subject vehicles.Of the eight reporting fleets, only one expressed concerns similar to the fleet submitting the VOQ.Of all the fleets contacted, none had experienced a crash where the throttle delay was a contributing factor.Autocar provided a modified direct wire throttle to the initial fleet as a customer satisfaction campaign.This configuration resulted in an improved throttle response.In light of the low rate of delayed throttle response on the subject vehicles and Autocar's actions to improve the throttle response on the complaint vehicles, further use of agency resources does not appear to be warranted.The closing of this investigation does not constitute a finding by NHTSA that no safety-related defect exists.The agency reserves the right to take further action if warranted by the circumstances.The ODI complaint cited above can be reviewed at: http://www-odi.nhtsa.dot.gov/owners/SearchNHTSAID using the following (ODI) number: 10471829