On your search for the best car diffuser, one of the many products you will run across is the UnderReef Car Air Purifier. This essential oil diffuser\/humidifier\/aromatherapy device is powered by your car charger port. Portable devices aren't usually adjustable beyond location, but this oil diffuser has a full 180-degree range-of-motion so you can easily position it for maximum efficiency.\r\n\r\nWhy We Like It - UnderReef Car Air Humidifier Diffuser\r\nThe UnderReef Car Air Humidifier Diffuser is an essential oils diffuser that plugs into your car charger port. This aromatherapy mini car portable cool mist humidifier can be rotated 180 degrees without leaking and holds up to 50ml of liquid. It automatically turns off after two hours to prevent dry burning.\r\n\r\nPerformance\r\nThis car air purifier\/humidifier easily fills your vehicle with a pleasant aroma. Essential oils come in many different scents, so you have an unlimited amount of options for your aromatherapy. Mini car charger port powered, this device holds up to 50ml of liquid which provides two hours of constant performance. Unfortunately, this device doesn't have a USB outlet, so if you want a device that can also charge your devices check out the Gulaki Diffuser Essential Oils Multifunction device instead.\r\nDesign\r\nThe UnderReef Car Air Humidifier is powered by your car's charger port. Portable, cool aromatherapy shouldn't take up a lot of space, and in this case, it doesn't even take up your cup holder space! The device has a maximum capacity of 50ml of liquids, burns through 25ml\/hour, and will automatically shut off after two hours of use (if you want a non-electronic diffuser, consider the RoyAroma Aromatherapy Essential Stainless Freshener instead). The tank can be angled within a 180-degree range-of-motion so you can have the device aimed wherever you prefer.\r\nValue\r\nThis nifty little device is very affordable, costing only $12.99 (for comparison, our #1 pick, the InnoGear Essential Refresher Ultrasonic Aromatherapy Diffuser, costs about $7 more). It has free shipping, but unfortunately, there are no free returns or warranty offered for this item. That is slightly concerning, as this product ranks lower than similar devices, scoring only 3.5\/5 stars based on 101 Amazon ratings. The most common complaint is device failure soon after purchase, which makes it hard to recommend this humidifier.\r\nUnderReef Car Air Humidifier Diffuser Wrap Up\r\nThe UnderReef Car Air Humidifier Diffuser is a great device when it works, but unfortunately, it is prone to failure, so we can't recommend it. While it may work great for some people, the odds are not exactly in your favor, so we would suggest checking out our list of the best car diffusers instead. On the plus side, if you do buy the device and it fails, you will only be losing less than $15.