I wanted to add CarPlay/Android Auto capability to my nearly twenty-year old car and as soon as I learned standalone receivers existed, I knew that was the direction I wanted to go. I started looking for a good candidate for installation inside existing navigation hood. It’s a little motorized retractable pod where Mazda housed the screen for the factory navigation system, and fitting into that pod will be the primary physical constraint. In addition to physical size, there are several other evaluation criteria:

Screen

Annoyingly, screen size is the next most important constraint, yet it isn’t something I can confidently determine. I want to buy a unit with visible screen area matching the factory navigation screen, so it fits perfectly in the original bezel, but the exact height and width are never specified. The best I can do is look for a “7-inch class” diagonal screen, excluding significantly larger and smaller screen sizes. I also excluded wide aspect ratio screens like this example. (*) A wide screen is a great idea for sitting on top of the dashboard, the intended use these standalone receivers. Showing more data without being too tall and blocking the driver’s view. But I want to fit into an existing 16×9 aspect ratio bezel, so those novel designs are out.

For the display panel, I personally prefer IPS panels for their color and viewing angles. Some units use a TN panel which will probably suffice. (The original navigation screen was likely a TN panel.) I don’t think they make VA panels at these small sizes, but they would also suffice. And finally, I’m not willing to pay the premium for an OLED panel here. Their stunning contrast ratio would be lost in the interior of a car, and there’ll be a lot of infrequently changing pixels risking OLED burn-in. Making OLED a poor choice for this application.

Most of these 7-in screens list their resolution as 1024×600. This is pretty low by modern screen standards, but it’s going to be mounted in a car further away than my usual computer and phone screen distance, so it might be fine. I’m confident it’ll be an upgrade from the factory navigation screen resolution! If resolution proves to be a limitation, I’ll come back and pay extra for a unit with a 1920×1080 screen.

[UPDATE: It would be nice if the device automatically dimmed the screen when dark. I forgot to look for that in my first device, it’ll be added to the criteria list if I shop for another.]

Touch Input

Capacitive touch technology has taken over everything, I didn’t see any of these receivers listed with a resistive touchscreen. My concern with capacitive touch is their sensitivity to environmental interference. A resistive touchscreen will only react to physical forces. A capacitive touchscreen might be affected by the plastic bezel, mounting hardware, or other electronics in close proximity. But given the lack of non-capacitive options I just have to give it a try.

Camera

Since these things are designed to sit on top of our dashboard, some (like the wide aspect ratio item linked above) integrated a front-facing dashboard camera. Since I want to bury mine inside the factory navigation hood, that feature would be useless for me. On a related note, several included either provision for a backup camera or comes packaged with one. This caught my interest. RX-8 rearward visibility is not great, and I’ve occasionally wished for a backup camera.

Audio

For audio output, these devices all have a little built-in speaker for when they’re sitting on the dash. Since I want to integrate it into my car, I want units with a line-level audio output jack. Some of these units can also act as a FM transmitter so we can tune in with the radio, which might sound better than the tiny built-in speaker but not as good as line-level audio signal.

They all have a built-in microphone for audio input, for use with Apple’s Siri or Google’s Assistant. Some of them have an audio input jack for an external microphone, and some have provision for an external button to activate voice commands. I never use voice input, so this was irrelevant to me.

Wired or Wireless?

I’m torn on whether to go for wired CarPlay/Android Auto or wireless. A wired interface will be immune to RF interference and will charge up my phone while in use. Wireless will be more convenient, and one less cable I have to route under trim panels in the car. I can go either way and if it proves to be a problem, I could buy a unit with the other connection method.

Winner

Criteria above culled Amazon listings down to about two dozen very similar products from brands I’ve never heard of. Not knowing how to evaluate differences, I do what most Amazon shoppers do: sort by price. I then clicked “Add to Cart” for a TTXSCAM T86 (*) which had the following features:

• 7″ IPS capacitive touchscreen with 1024×600 resolution.
• Bundled backup camera, no front facing dashcam.
• Audio-out jack in addition to built-in speaker and FM transmitter.
• Built-in microphone only. No audio-in jack or voice activation button.
• Wireless CarPlay and Android Auto

This is a very affordable unit. I thought I would start here and, if I find anything annoying, that would teach me reasons to justify going upscale. Keeping things cheap also means it’ll be less intimidating to modify as needed to fit my car. Once it arrived, I looked over everything that came in the box.

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(*) Disclosure: As an Amazon Associate I earn from qualifying purchases.