You're joking aren't you.
Nope.
They don't even have folding seats or power fold mirrors as standard.
Oh no. I'm not saying these are not useful options to have but it's a far cry from the days when the wrong 520d had a manual gearbox, halogen headlights, a tiny nav screen and climate control that lacked a sun load sensor.
The reality is that few G30 have no options at all - so any car you find will have everything you need and a couple of nice to have items on top, too.
The base specification contains everything that's a must have - making it far easier to find a nice example.
Correct HK audio is a must the base audio is utterly pants.
I have HK Audio. It's excellent and I really like it. I've also had base audio and it was fine. In an ideal world, I'd not want a car without HK audio but my point is that the base specification has everything 'must have'. HK is not a 'must have' its a preference.
Fortunately because what matters most to people is huge wheels and bright blue brake callipers many cars have M Sport Plus optioned which does include the HK.
I would want active cruise, 360 cam and keyless entry but I guess others priorities are different, you won't find many 20d's with those options.
You won't find many G30 full stop with those options particularly active cruise. You've been spoiled by the hilariously amazing specification of your 530e - even now active cruise is probably the rarest 5 Series option around - it's madness given its been standard on a Golf for about 8 years now but it's the way things are. If you decide you want active cruise, HK and 360 parking cameras with a 25k budget then give up now because it's not going to happen very easily.
Lumbar support isn't standard, be sure to get that! Base leather is quite poor quality and lots of owners have seen the coating fail at a surprisingly low age, and the seat bolsters cracking. Doesn't affect better grade leather.
A 520d with Driver Assistance Plus, Nappa comfort seats, 360 cameras, HK sound. It would be amazing if it were this easy!
There isn't anything wrong with the standard leather either which again is fortunate as people in this country just don't spec much on these cars so used you really do end up having to stop being so picky unless you want to spend 9 months looking for the car and then have to have it with beige paint or something when it does finally appear.
The lowest spec G30 I've ever driven had no optional equipment at all and the highest spec had Driver Assistance Plus, nappa leather, cameras and even night vision. It was a wonderful thing so I under the difference between cars with and without these things. But a car without those things isn't exactly terrible, is it. Which like I said is fortunate because in the UK market it's all about 20 inch black wheels and M Performance stickers not generous interior specifications.
Every purchase like this is a compromise. Even your huge mega spec example (the specification of which I am very jealous!) has a massive compromise with its missing cylinders which to me would be a bigger must have than anything else you've mentioned