Realistically nobody is going to buy a 318. It is there to make you buy the 320 for just that little bit more.
My trusty inflation calculator and car magazine from 2013 shows that inflation-adjusted, an F30 320i would cost the equivalent of R725K today. We are sitting at +38% over what we 'should' be paying for one if it was purely inflationary effects at play. At the same time the N20 equipped 320i had a fair bit more power than 115kw. It really has been bad on that front. Generally cars in other markets are not that different in price from the outgoing generation (few % which can be written off in the extra tech/performance they bring in). These %s are great on paper but a few % on 500K and on R1.5M are very different things in practice.
A 335i would cost the equivalent of R1.1M for reference. You could argue at the higher end it is not as bad since the gaps are still comparable - just that the lower tier models seem MUCH more unpalatable because of it.
X3 M Competitions are no brainers for the money they are going for at the moment.
We actually have a lot of slept-on cars while everyone is worried about either new cars or what was the 'last best' and looking for rubbery manuals:
Z4 2.0i with the B48 (its actually fun to drive)
Z4 M40i with the B58
X3 M40i
AMG GT/GT C/GT R
C63 C205 Coupe (many are shitboxes though)
SLS Roadster (the gullwing is double or triple this)
2018-20 Cayenne Turbo E3
Giulia QV (provided you service at a specialist)
F-Type R
When people come with "what can you buy" stories and point to a Golf you have to wonder

. I suppose the real question is "what can you rent" since to buy some of these, you won't be able to use the lease gymnastics