Search Results

This research was performed to experimentally determine how the amount of fuel used to accelerate an initially stationary vehicle to a constant cruising speed depends on acceleration level. Initially stationary vehicles were accelerated at different rates to a constant cruising speed on a test track, and the amounts of fuel used to travel a fixed distance from the starting point were measured. By subtracting the amount of fuel that would have been required to travel this same distance at the cruising speed from the measured amounts, estimates of the additional fuel used to accelerate from standstill to the cruising speed were obtained. These estimates were then examined as a function of acceleration level, which was characterized by the time taken to reach the cruising speed. Tests were conducted for cruising speeds of 48 km/h, 64 km/h and 80 km/h. Factors investigated included different vehicles (8 in all), engines (L-4, V-6, V-8), and fuels (gasoline and diesel).

A number of studies of the effect of traffic conditions on fuel consumption and emissions are reviewed. A model based on driving vehicles in traffic is described in which the fuel consumption of a vehicle in urban traffic is expressed as a simple function of trip speed. Data from a variety of sources, including additional field data, detailed computer simulation, the same vehicle tested on different fixed urban driving schedules, and small segments of the Federal Test Procedure (FTP) have been all shown to fit the model. A similar model of HC emissions as a simple function of trip speed is derived from analyzing small segments of FTP data. Data from a variety of sources, including published EPA relations, detailed computer simulation, and dynamometer replication of street data have been all shown to fit this model. No simple models were found for CO and NOx.