Is the Porsche 911 a good investment?

The thesis

The 991 R is the unicorn: 991 units, 4.0L NA flat-six, six-speed manual, no rear wing, pure GT3 RS mechanicals wrapped in a purist's dream. Production was deliberately constrained to create instant collectibility, and it worked—prices soared from £136k new to £500k+ almost immediately. Today UK examples trade £500k–£850k depending on spec and miles. The 991 R is already a blue-chip Porsche, sitting alongside the 997 GT3 RS 4.0 and 964 RS as a modern icon. However, the bulk of appreciation has occurred; the R is now 'mature' and stable rather than a growth candidate. Buyers at this level secure a definitive modern 911, but should not expect further dramatic gains.