Filing a complaint against a Cambridge taxi with the CPD's Hackney division will get you a remarkably quick response from CPD. I reported a taxi driver for parking and then driving in a bike lane on Mass Ave last year. Within a few days I got a response back from a CPD Hackney division officer. They claimed to have spoken to the taxi driver who gave them a sob story about having a medical emergency (diabetic and needed a donut from dunks was their claim). The officer really didn't seem to give a shit but they did at least speak to the driver. And that driver now has a complaint on file if anything serious happens in the future.

So needless to say: report them if you want, but expect nothing to come out of it. Probably worth it just so that driver thinks twice about fucking around in the future. That's what I like to think my report did. But who knows. CPD really doesn't seem to like doing any real work.