Since V-Tex is a "synthetic" leather and more like vinyl, I would think to treat it like vinyl. I`ve had great luck with Meg`s Detail Line D101 All-Purpose Cleaner (the green stuff) diluted 6:1 for cleaning vinyl. I`ve used Optimum`s Power Clean on REALLY dirty vinyl in spots, but I "dislike" (AKA hate) the lingering smell, even when rinsed. I`ve used Aerospace 303 Protectant for many years on vinyl with great success after trying it with suggestions from fellow Autopians .
That said, I think Nextzett Plastic Vinyl Deep Cleaner Plastik Reiniger and its twin plastic/vinyl associate Cockpit Premium might be a better choice for this particular material.
Oh yes, if you smoke inside your VW with this material, watch out! This particular material will burn easily from a very small ember and you will be left with a large burn mark, more so than vinyl or leather that you can catch sometimes by quickly patting it out. (Disclaimer: Info is from another blog on VW`s, not my personal experience)
And if, by chance, you ever do spill something sticky on the seats and have to unplug those hole perforations, try using a ROUND wooden (birch) toothpick for the holes. Be careful though, because the tip can break off if you get aggressive and try "digging out" the offending clogging material when tilting the toothpick at an angle. I use a circular wiping pattern with the very tip of the toothpick inserted in the center of the hole and try to displace the clogging material from the hole. It`s "better" than a thick metal needle, though, as the wood breaking acts like a safety before you rip/scratch the leather or V-Tex. You may need to use several of them if you have a lot of holes to clean, and yes, it is VERY tedious and time consuming to do.