Representative road load test procedure

Peter Smeds – Swedish Transport AdministrationIddo Riemersma – Transport & Environment

WLTP-DTP-LabProcICE-029,22-11-2010

Problem descriptionCustomer expectation:

Realistic fuel consumption figuresRequired:

Test procedure aiming at representative road load for production vehicles

Road load not tested on production vehicle, but on a pre-production vehicle

Many ‘flexibilities’ in current ISO 10521 road load test procedure

Manufacturers need a level playing field

Road load data

TŰV Nord showed reductions of CO2 emissions up to 10% on NEDC test cycle for reduced road load(-20% at 20 km/h, -10% at 40 – 120 km/h)

Source: presentation at Vienna meeting, document WLTP-DTP-LabProcICE-023

Flexibilities in current ISO 10521Vehicle preparation / adjustmentsWheel alignment

> fixed tolerance to avoid unrealistic range of settings

Brake pads> mandatory braking action before testing

Other adjustments or setting issues?

Flexibilities in current ISO 10521Test tracksClimatic conditions (tracks in hot climate

beneficial)> review and adjust correction formulas

Asphalt type> only allow commercially available asphalt on the track

Other track issues?

Flexibilities in current ISO 10521TyresWear

> representative alternative: 30 – 40% from new to bald

Pressure> require at least the same tyre pressure

Choice> require at least same dimensions and rolling resistance

Other tyre issues?

Flexibilities in current ISO 10521Vehicle characteristicsWeight

> require at least the same vehicle weightBody

> require at least the same aerodynamic characteristics

Other vehicle related issues?

Alternative approachFeed forward approach

Feed back approach

> Feed back loop via CoP and/or in-use compliance

Coast down test

vehicle

Production vehicle

Road load dataRequiremen

ts

Coast down test

vehicle

Production vehicle

Road load data

Requirements

Road load data

Requirements

RequirementsRequirements

Requirements

Conclusions &recommendationsIdentified flexibilities in ISO 10521 can be

solved to some extentSome gaps will stay and tolerances have to be

allowed Best guarantee for a representative road load a

feed back approach Existing legislation and targets for CO2 need

to be reviewed if RLD procedure is changed

Next stepsA document is being prepared with an

inventory of issues in ISO 10521 and options for solving them.

This will be input for further discussions within the ICE LabProcesses group, generating feedback

A proposal will be prepared for an improved RLD procedure in the draft GTR.