Mercedes-Benz W109 buyer's guide

The W108's plusher, air-suspended sister — home of the 6.3.

Years: 1965–1972 · Models: 300SEL, 300SEL 3.5, 300SEL 4.5, 300SEL 6.3

Overview

The W109 is the W108 body with a longer wheelbase, self-leveling air suspension, and a richer interior of wood and leather. Its crowning model is the 300SEL 6.3 of 1968–1972, which put the 600's V8 into the sedan and was the fastest production sedan of its day. Fewer than 10,000 W109s of all kinds were built, against more than 350,000 W108s, so rarity is built in.

Engines

The 3.0-litre M189 fuel-injected six in early cars; the M116 3.5 and M117 4.5 V8s; and the 6.3-litre M100 V8 in the 300SEL 6.3.

What to check

• The air suspension above all: time how long the car holds its ride height overnight, and price in the bellows, leveling valves, and compressor if it sinks. A full system rebuild can cost more than a project car.
• The same structural rust areas as the W108 — floor pans, sills, and trunk floor.
• On the 6.3, engine oil consumption and the condition of the mechanical injection pump; M100 parts are expensive and some are scarce.
• Chrome and wood condition: the W109 carries more of both than the W108, and replating and re-veneering add up quickly.
• That a car 'converted to steel springs' is priced as what it is — a car whose defining system has been removed; converting back is a major job.

Values

The 6.3 is worth several times any other W109 and is a genuinely collectible car; the V8 3.5 and 4.5 follow. Documentation — especially air-suspension and engine history — moves prices more than cosmetic freshness.

Buying tips

Never buy a W109 without the overnight ride-height test, and treat a complete parts car or a spares package as real value: air-suspension and trim parts are the ownership bottleneck, not the engines.

See the 23 W109 cars currently listed.