The FTP-75 and the FTP72 are two variants of the EPA Urban Dynamometer Driving Schedule (UDDS). The FTP-75 cycle is derived from the FTP-72 by adding a third phase of 505 s, identical to the first phase of FTP-72 but with a hot start. The third phase starts after the engine is stopped for 10 minutes. Thus, the entire FTP-75 cycle consists of the following segments:
- Cold start transient phase (ambient temperature 20-30°C), 0-505 s,
- Stabilized phase, 506-1372 s,
- Hot soak (min 540 s, max 660 s),
- Hot start transient phase, 0-505 s.
The emissions from each phase are collected in a separate teflon bag, analyzed and expressed in g/mile (g/km). The weighting factors are 0.43 for the cold start, 1.0 for the stabilized phase and 0.57 for the hot start phase.
It is important to understand that the bag weightings for the three phases are designed to simulate running the stabilized phase a second time. This is done by weighting the second phase to be the same as the total of the first and third phases. Thus, the cycle itself consists of only the first and second phases, with the first phase repeated and the second phase simulated with bag weighting. Hybrid vehicles are required to actually run this forth phase, instead of simulating it with bag weighting.
The following are basic parameters of the cycle:
- Distance traveled: 12.07 km (7.5 mi)
- Duration: 1369 seconds (505s phase 1, 864s phase 2)
- Average speed: 31.5 km/h (19.6 mi/h)
- Maximum speed: 91.2 km/h (56.7 mi/h)
For emission certification, vehicles must meet the applicable FTP emission standards. From model year 2000, vehicles have to be additionally tested on two Supplemental Federal Test Procedures (SFTP) designed to address shortcomings with the FTP-75 in the representation of (1) aggressive, high speed driving (US06), and (2) the use of air conditioning (SC03).
Fuel economy values are calculated on the basis of FTP testing for the city rating, while the highway rating is determined based on HWFETtesting.
The FTP-75 cycle is known in Australia as the ADR 37 (Australian Design Rules) cycle.