I have seen people with the car gps on bikes. Some are solid mount, some custom made mounts, some off the shelf adjustable smart phone mount. A nice trick in the rain is a sandwich bag and a little duct tape.

Thanks Bret
I wonder if the screen will be readable in the sunlight. Nothing ventured nothing gained. I will give it a try
Johnb

You need a GPS that will export the voice via Bluetooth or direct plug. You will never hear the voice from the speaker with all the wind noise on a motorcycle. This important feature rules out almost all Garmin car products, except a few a decade old. (It's a clever way to sell their highly over-priced Garmin motorcycle products.)

Also, don't plan on placing your GPS in a confined area in your tank bag or it may overheat.

Basically if you buy one of the TomTom products for motorcycles (like TomTom Rider), you can use that in your car, but doing the reverse is usually more difficult.

Generally, if you have a small windscreen, you can hide a RAM mount out of the wind and simply use your cell phone with WAZE or Google Maps.... as long as you have cell service.