Garmin - let us set a speed threshold to stop recording activities!

I keep doing the same :) Fortunately Garmin introduced possibility to edit activity duration in the mobile app, so now it's relatively easy to fix that.

Aren't you interested on seeing the results of your exercise after you are finished? Like heart rate, distance, changes in VO2Max, speed, and how long rest time the watch recommends? I am usually too curious about these data to forget stopping the logging. I am more likely to forget starting it. 

I am.  But it's not always top of mind after a ride, hike, etc..... And all the data from the activity is usually worthless after 10 or 15 minutes of driving.  If the watch would stop at some preset speed it could all be salvaged.  It's the simplest concept and I can't believe I have to post this request.  

You could also imagine a geo-based mode for many activities.  Auto-stop when I get within X meters of where I started, e.g. your car or trailhead or whatever.

For step based activities like running, walking and hikes, it is easy for the watch to detect that the speed goes up and the cadence is close to zero. That means you are in a car or train or something. It could vibrate and sound an alarm to remind you to stop the workout. 

Interesting. Can't see how in my mobile app. Can you say how exactly?

Just set a speed threshold for it to pause and prompt if you want to stop or continue

My app is not in English, so the names of the actions may be a bit different, but it goes like this:

1. Open the activity

2. Edit activity from the top right corner menu

3. Scroll down and launch "Shorten activity" (or sth like that) - then you have the options to change the total time, start time or end time. And there's a chart showing the pace, so you can easily find when the car ride started.

That feature was introduced a couple of versions ago.

Many thanks for responding.
I'm still not seeing how this works in the "App".  For the sake of clarity, are you referring to Garmin Connect App? 
(I'm using Android version 5.4.1 so maybe it's just not an option there).