What type of power do modern milk floats usually use?

Modern milk floats usually use battery-electric power.

Milk floats were developed for short, repeated delivery rounds, making electric drive especially suitable. Their batteries can be recharged at a dairy depot, while the vehicles produce very little noise—an important advantage when delivering milk in residential areas during the early morning.

The vehicles are generally small three- or four-wheeled delivery trucks with modest power output. That design favors low-speed maneuvering, frequent stops and easy access to doorsteps over long-distance travel or high speed. Milk floats were once common in Britain and other European countries, where local dairies delivered fresh milk directly to homes.

The answer does not mean every milk-delivery vehicle today is electric. Some dairies replaced electric floats with petrol or diesel vans as delivery rounds became longer and less profitable. Historically, milk was also delivered using horse-drawn floats, especially from the late nineteenth century until the 1950s.