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This paper assesses the impact of the cold start phase of light duty vehicle use on energy use based on a review of large set of vehicle emissions test data from Canadian and U.S. Government databases. The data indicate that, at 24°C test ambient, a 20% increase in fuel use is measured in the “cold” Bag 1 driving compared with the “hot” Bag 3. Lower ambient conditions increase this penalty in a linear manner such that at the -6.7°C test condition, the penalty rises to 40-80%. The paper then integrates the laboratory tests data with vehicle demographic and usage data gathered from consumer driving studies. Included in this data are results from a small pilot survey in Vancouver, which directly measured instantaneous fuel consumption of vehicles in consumer use. These data sets were then used to estimate the total “extra” energy used during the cold start phase of driving.

The Province of BC requires all light duty vehicles in the lower mainland to pass or conditionally pass an emissions inspection as a condition of license and insurance renewal. Vehicles converted to natural gas and propane fail emissions tests at higher rates than comparable vehicles run on gasoline. Work is described to investigate the emissions performance of vehicles fitted with after-market conversions. FTP 75, Hot 505 and BC AirCare test cycles (total 74) were performed on a variety of vehicles (total 20) which were split between dual-fuel and mono-fuel using propane or natural gas along with gasoline. All but three vehicles were supplied by the manufacturer to run on gasoline with closed-loop air/fuel ratio feedback. The after market conversions consisted of both open-loop and closed-loop feedback systems for the gaseous fuel systems.