> A fast horse can run more than 40MPH which about all you can expect from a car in a city
A slow car can go much more than 40 mph. Both cars and horses may be practically limited by traffic most of the time in crowded urban environments, but cars are still faster, even in most cities, on both peak and practically-attained-average speeds.
"The Model T had a front-mounted 177-cubic-inch (2.9 L) inline four-cylinder engine, producing 20 hp (15 kW), for a top speed of 40–45 mph (64–72 km/h)."
Being faster than horses isn't why cars won. Given the choice between a modern car and a hypothetical horse with the same or higher top speed, most people are still not going to choose the horse.
A slow car can go much more than 40 mph. Both cars and horses may be practically limited by traffic most of the time in crowded urban environments, but cars are still faster, even in most cities, on both peak and practically-attained-average speeds.