I've got one of these Viofo A129 Dual Camera sets (links to Amazon page illustrated below) and they're superb.
Easy to fit DIY (or if you don't want to DIY then any auto-electrician will fit), very small and unobtrusive, with great, clear recordings both day and night.
Each camera manufacturer will recommend their own microSD cards but these Samsung Pro Endurance cards are amongst the best out there, if not the best and have an excellent reputation.