Used Mercedes-Benz 300

What to know before buying: Mercedes-Benz 300

From 5 forum threads and 2 press tests · updated 12/10/2026

What the reviews say

• W123 owners praise its ride comfort and handling, but describe the 300D's acceleration as unhurried.[1]one source
• The 2019 W205 C300 is described as well engineered, well built and generally reliable, though servicing can be expensive.[6]one source
• The sole S 300 review rates comfort and reliability at 5/5 and handling at 4/5, while also praising material and build quality.[7]one source

Typical faults

• One 1990 SL 300-24 ran on only 4–5 cylinders after sitting for 2–3 weeks, with hunting idle, exhaust bangs, heavy fuel use and poor performance.[2]one source

  1990–1990 · 300-24

• One W123 300D diesel engine would not shut down even after the ignition key was turned and removed.[3]one source

  300D

• One W140 S300 TD developed a warm-idle vibration that was stronger in Drive and after longer journeys, but eased in Neutral or Park.[4]one source

  S300 TD

Which engine and version to take

• The naturally aspirated W123 300D diesel is repeatedly described as exceptionally durable; examples beyond 500,000 km are mentioned, though no longer operating perfectly at that mileage.[1]one source

What to check at the inspection

• Test a 1990 SL 300-24 cold after an extended rest: confirm all cylinders fire, idle is steady and the exhaust does not bang; also assess fuel use and performance.[2]one source
• On a W123 300D, test engine shutdown with the ignition key; the engine should stop when the key is removed.[3]one source
• Fully warm a W140 S300 TD and check for idle vibration in Drive with the brake held; compare it with Neutral and Park.[4]one source
• For a 1992 W124 300D, verify its actual condition and mileage credibility; forum contributors warn that passing inspection alone does not prove the car is in good condition.[5]one source

Verdict

Sources

1. [1]bmwslo.com — Mercedes Benz W123 - Stran 9 - Avtomobilizem · forum
2. [2]forum.mbentusiastklubb.no — SL 300-24 Motor problem - Teknisk avdeling · forum
3. [3]bilforumet.no — W123 300D - problemer med å stoppe motor - Mercedes · forum
4. [4]forums.mbclub.bg — S300 TD W140 - Проблеми и ремонти · forum
5. [5]forum.mbclub.lv — Apskatīt tematu - Par cenām MB-300D · forum
6. [6]carsguide.com.au — Mercedes-Benz C300: What are common problems or faults? · press
7. [7]auto.ria.com — 1 отзыв о Mercedes-Benz S 300 · press

Spotted an error? Tell us