We have quantified the average speed of automobiles on a dozen highways and expressways flowing into New York City from Long Island, CT and New Jersey, to quantify how traffic ebbs and flows over time.
Traffic is most severe at 4-5pm, second worst at 8-9am, but least severe at 4-5am. The data in the file are from 2H19.
We can compute average vehicle fuel economy, as a function of these traffic speeds. Moderate-severe traffic congestion curtails average vehicle fuel economy by 15-45% on highways leading in to a city.