Record your ride with a dashcam and you’ll be surprised at the ways in which the best in-car video recorders can protect you. Of course it’s very handy to have a video clip of the moments before, during and after any car accidents you may suffer or witness on the road. But more than that, the best dashcams on the market have alerts that can help prevent trouble in the first place. 

If you buy a dashcam with GPS and keep its mapping up to date, you often gain speed camera alerts, and even warnings when you’re over the speed limit. Dashcams don’t help you to navigate, but some of them will sound an alert if you’re gently drifting out of your lane, which we think could be a life-saver, particularly if fatigue is the reason for it. And if you’re happily driving along and the car in front suddenly brakes, an alert will help reinforce your natural reactions.

We’ve been busy testing dashcams for caravanners just recently and now you can browse a selection of dashcam reviews before you make up your mind which one to buy. We’ve tested the RAC 05, at £149.99, the Garmin Dashcam 20, at £129, and the Mio MiVue 658 WIFI, at £142.96, the Tsumara G3, at £139.99, and the Transcend DrivePro 100, at the low price of £64. We tested the Cobra Drive HD CDR 840, at £99.99 and the RAC 04, costing just £59.99. Then we compared the Next Base IN-Car Cam Duo, at £199.99 and the Trackvue DV300, at £99.

The Cobra Drive HD CDR 840, priced at £99.99, is similar to its far cheaper sibling, the CDR 820 (£64.99), except that the 840 we’re reviewing here comes with inbuilt GPS. But this is GPS in its most basic form: it’s purely for allowing analysis of speed and positional data – along with the video – should you have an accident. The Cobra Drive HD CDR 840 has a G-Sensor, which means that it can detect impact speeds and G-forces and record these as part of the evidence.

Continuous loop recording, which is pretty much standard for all dashcams, ensures that the filming carries on even when your memory card is full. The camera just overwrites the old footage with new. 

There is free PC software included in the package, though, so at least it’s easy to view your footage on your computer and save anything you need to keep. This is probably just as well, since the screen on the dashcam itself is tiny, being just a 1.5in LCD screen.

Optically, there’s very little to separate the two Cobra models, and the 840 records the view you see through your windscreen in 1080P Full HD Video. It’s a little disappointing that the field of view is relatively narrow at 118° on this more expensive model, especially given that this Cobra Drive HD CDR 840 model is quite a bit bigger than its sibling, measuring 2.4in high, 3.9in wide and 1.5in deep (60.96mm x 99.06mm x 38.1mm).

However, the increased size does at least make it much less fiddly to use and handle. Outputs are USB and HDMI ports. On the plus side, too, it does come with an 8GB MicroSD memory card and suction-cup windscreen mount, so you can use it straight out of the box. Also in the packaging you’ll find a cigar-lighter socket adaptor and lead and a mini USB-to-USB lead.