Ford's hybrid options have almost always been among the worst in the market. The article points out it's a terrible hybrid that barely gets 2mpg better mileage

Ford's hybrid options have almost always been among the worst in the market. The article points out it's a terrible hybrid that barely gets 2mpg better mileage on the EPA cycle. It's not cost effective for your average consumer, and there are much better hybrids available, so consumers aren't buying them. However, police spend so much time idling and have so much electrical gear, they see a much, much bigger gas savings that aren't reflected by the EPA cycle. They also put lots of miles on the vehicles, so even if it was only 2mpg, that'd still justify the extra capex...but they also get all the benefits of powering all their gear. Keep in mind that cop cars go through regular lead acid batteries like candy.