I bought the Nextbase GW522 when it was on offer at Halfords and had it fitted for £30. If you’re prepared to put a bit of effort in, it’s a good camera and records in 4K at 30fps. It comes with a polarising filter which is invaluable on the MX-5 because of the glare from the bonnet.
Plus points are a year of free SOS (it calls help if you have an accident and are unresponsive), built in Alexa which actually works with last weeks firmware update (so I can open my garage door as I pull into the street), reasonable video quality, magnetic mount so easily detached if you are top down or have scum in your village.
Cons. It can vibrate a bit on the suction mount so use it for a while then switch to the included 3M sticky mount, mag mount is very powerful (but you eventually get the knack), support is patchy and you have to really use Nextbase SD cards, viewer software is buggy and ALWAYS shows your speed so make sure you behave before an accident !