The goal of automotive regulation has always been to walk the line between offering OEMs an implementable procedure for certification and representing real-world driving conditions that drivers will experience with a vehicle. The inherent variance of operating conditions and drivers makes it difficult to predict the actual performance, fuel economy, and emissions levels of vehicles when they are sold to customers. On the other hand, OEMs must be able to ensure that multi-billion-dollar vehicle programs will be able to meet the regulatory burden before reaching production and therefore they need clear testing procedures and guidelines to use during development.
The Need for a Better Way
Historically, vehicle certification for fuel economy and emissions has been done on chassis dynamometers with fixed-profile driving cycles. European regulation was based around the New European Driving Cycle (NEDC) while the US used the Federal Test Procedure 75 (FTP-75). The cycles were designed to mimic the vehicle speed and load range that a typical customer might expect to impose on the vehicle during normal operation.