Filling while driving? Um.... There is this thing called "pulling into a safe space to stop." Honestly I can't imagine filling while driving, ever, period, regardless.
I should note, about the ares, that my topfill cap doesn't always stay completely in place. It will slide slightly, and it's also not the "easiest" slide topfill, to be honest. You have to look down and see that you are pushing in the right area, and it's a very TINY marking. IDK if anyone else has that issue with the ares, but my top cap will slide (a very short distance) and I do have to periodically check it. It's never leaked or anything, so it doesn't slide all the way, but I do have to "click" it back in place on occasion, and I don't think it would be a fantastic "topfill" to use while driving, in fact I rather think it would be pretty dangerous. Maybe she's more dexterous than me, but if she has to learn to build on top of it, well, I'd say it's not the greatest choice, for her "needs" which are honestly pretty ridiculous, she should be checking if her vapes need filling BEFORE she turns on the ignition, if you ask me. That's an accident waiting to happen. I would not suggest the Ares either, it requires concentration to fill, and it's not optimal for this use (although in my opinion NOTHING is, and it's a perfectly easy problem to SOLVE ANOTHER WAY.
Just... I hate the idea of car accidents due to filling vape on the highway. That won't go over well and frankly your wife could be badly hurt and/or kill someone else.
Just my opinion, as always. The ares is a 4 ml tank, though. She should FILL it before she gets on the road, not during it. Oh my.
:Anna