Audi S8
Why 6.3: A twin-turbo V8 doing 563 hp through a nearly silent mild-hybrid system, wrapped in the same sheet metal as a diplomat's A8 — the S8 is built for buyers who want the pace without the RS badge announcing it. It gets driven the way any big AWD autobahn sedan gets driven: continent-crossing miles, not lap times.
Layout
Natural habitat
Ride comfort
Sound
The 4.0 TFSI has real V8 weight when the exhaust valves open and it never sounds strained doing anything. But this is a limousine with active noise cancellation working against you, tuned throughout to be inaudible. Deep, distant and deliberately suppressed.
8-cylinder · turbocharged · 6,800 rpm redline · rated 4.6 / 10 for engine sound
Market value
Median asking price, good condition · €109k (2020) → €72k (2026), trending down · illustrative data
Child seats · ISOFIX
ISOFIX and top-tether anchors are standard on both outer rear seats.
The A8/S8 front passenger seat has no ISOFIX anchor at all — unlike every smaller Audi from the A3 up to the A7, which all offer at least an optional front mount. A belted rearward-facing seat is still possible with the airbag switched off.
A genuine flagship-saloon gap in Audi's own range — the front ISOFIX bracket sold for A3/A4/A5/A6/A7 doesn't have an A8 fitment listed.
Audi A8 owner's manual (ISOFIX section); VAG parts catalogue (front ISOFIX bracket listed for A3/A4/A5/A6/A7, absent for A8)
The long version
S8 buyers are disproportionately people who already know what an RS6 or an M5 costs to insure and attract, and who decided the quieter badge was worth the trade — the same basic twin-turbo V8 architecture underpins both the S8 and the RS6 Avant, just tuned down and wrapped in a longer, heavier body most people read as a diplomat's car rather than a driver's one. That anonymity is the actual selling point: real miles get put on these, mostly at license-losing speeds on unrestricted autobahn sections, precisely because nobody looks twice. Depreciation has been steep and predictable, standard for any six-figure German AWD sedan, and the used-buyer pool skews toward people chasing exactly that math rather than badge cachet. It is the most useful car in this index that nobody at a cars-and-coffee meet will recognize.