Nope you added in something I didn't.
"and a third sentence stating that you were curious to see if your Beetle was going to do what your Passat did."
All I said is I will see what the Beetle does. Just 3 statements no comparisons.
There's something peculiar about this particular forum that I never see anywhere else, and of which I fall into myself, about nitpicking the most ridiculous points in posts.
That culture seems to have been well cemented before I joined and presumably will persist long after I'm gone. So with that out of the way, let's see what we can see:
"My old 2013 Passat made it at least 10k between fills. I will see if this one does." is literally a comparison between whether your Beetle is going to do what your Passat did.
If you wrote, "I will see if this one does." in a vacuum no one would know what you are even talking about. If you actually did write, "I will see what my Beetle does" (you didn't, but you write in this latest post that you did), no one would know what you were waiting to see your Beetle do.
If you wanted a non-comparative, stand-alone statement it would have to be written thusly, "I am curious to see how much Ad-Blu my 2015 Beetle consumes." If that was your intention the inclusion of your 2013 Passat's Ad-Blu consumption in the same paragraph is superfluous in addition to being a non-sequitur to the question of how much your Beetle consumes.
Now you have a complimentary English composition lesson from your local professor. What you do with it, however, remains to be seen...