Mr. Silberholz gave a brief summary of the work achieved during validation test program 1 (pages 3 to 10 of HDH-15-04). He reported that extensive changes on models and model structure have been made. The new structure is component library based and enabled implementation of a flexible signal data bus, which allows adding more signals on the data bus. There was positive feedback from and good cooperation with the OEMs. The next model release is planned for the end of October, and would need to be tested again by the OEMs.

It was agreed that the additional testing of the models should not be a show-stopper for the drafting work. Mr. Silberholz confirmed that the models are described well enough for the drafting process, and could be inserted in their current stage.

Mr. Six presented a detailed analysis of the HDH drive cycle (WHVC with road gradients) on pages 11 to 33 of HDH-15-04. Parts of the investigations were done in conjunction with the chassis dyno tests at JRC. He concluded that the minicycle approach very well aligns WHVC and WHTC. This is considered a solid basis for the new test cycle. The approach considers added and removed payloads for positive and negative work, thereby matching of positive WHTC work independent of test weight (i.e. slopes will adjust work). A great benefit is that negative work is independent of test weight, so that adequate recuperation energy is always available. This better reflects real world operation for different payloads. A summary of the methods analyzed (minicycle, 30 sec average, individual slope, fixed slope) is shown on page 32. The final test cycle proposal of the institutes is a minicycle approach with positive and negative WHTC work, which is a clear improvement over the flat WHVC approach.

The detailed test results are shown on pages 36 to 48 for the Volvo bus and on pages 50 to 59 for the MAN bus. An analysis of the Iveco results is not available, since HILS modelling is still under construction. Additional chassis dyno tests are planned for early 2014.

Mr. Silberholz presented open issues for the drafting on pages 61 to 75 of HDH-15-04. Those issues were discussed in detail and will be taken into account during the further drafting process. The most prominent ones are listed below:

• Handling of gearboxes and shift algorithms; the Japanese regulation allows both generic and OEM specific model for automatic transmission.
• Definition of the rated power of a hybrid system; institutes were asked to check the US EPA approach and to make a proposal.
• How to deal with vehicles which by design cannot reach the maximum WHVC speed; it was suggested to scale power down, but EPA raised some concerns; Japanese approach should be checked.
• Work (engine or system) to be used for the emissions calculation. Mr. Dekker made clear that NL have concerns about the systems approach. The chairman concluded that there seems to be some diverging views within the group and that this will be an important topic to be discussed at 16th HDH meeting.
• Equivalency between post-transmission powertrain test, HILS with verification on chassis dyno and HILS with verification on system bench (pre-transmission powertrain test).