1990 Mercedes-Benz W124 300E M103 petrol from Italy
By moving to KE-Jetronic - due to the anti-pollution norms - Mercedes-Benz probably has lost part of its legendary reliability. This is, at least, my thought.
Electronics are a nightmare: first failure was the EHA sensor, making the car prone to stop randomly and suddenly at every speed. No way to switch on the engine before 5 minutes to 15 minutes max; I had to wait for that random time, then the engine ran smoothly like nothing had happened. This issue required a long examination to be found by the authorized Bosch workshop, being able to find the root cause and substitute the EHA for 400 Euro (an additional 8h of manpower was added to the final bill).
Months later, the potentiometer of the mass flow sensor was the root cause of a rough running at idle and up to 2000 revs; sometimes the car was going to stop (this last one cannot be replaced, you need the mass flow sensor new, which costs 10 times the potentiometer). I paid 208 Euro for a revised unit and 6h of manpower to search for the root cause.
I was obliged to change both the roller bearings of 5th gear, otherwise rough running - like you are traveling over a rough concrete surface - was present between 100 to 130 km/h: you can guess how terrible a motorway trip was at 140/150 km/h, risking a fine, or living hours at 90 km/h with a truck on your back and another one in front of you.
Unbelievable - in a Mercedes-Benz - that the plastic covers of the rear lights cracked (even if not broken): I understands 20 years of sunlight, but how does my previous BMW after 30 years have no damage, even if very small?
I bought this car because of its 138000 km in 20 years: a warranty of the real odometer mileage was its first owner, who sold to me informing me that he kept the car stopped in a garage for 95% of time in the last 6 years (2004 to 2010) because of the use of a city car after his retirement. This obliged me to have a full service of the 300 E, but probably it was not sufficient to neutralize the bad effect of the long stop, which contributed to the reliability failures.
Another reason for buying was it had plenty of options: automatic conditioned air, leather seats, front power seats, power windows, power sunroof, central locking and a lot of minor gadgets. To be demanding, only automatic transmission and light alloy wheels were missing.
Great comfort: during city running you are not able to feel any noise, unless you turn the engine at high revs (more than 4000), which is not possible in a town street. On a highway journey, you can hear only the tire sound, being the air noise is present only over 130 km/h and engine roaring only after 4000 revs (about 160 km/h in 5th gear).
Also economy is fairly good for a car of its size: highway trips at 130 km/h require 9.5-10 liters for 100 km, and town use requires 7.5 to 8.5, which is already good for its size and time.
Driving is good, but I feel a heavier behavior in comparison with the more reactive BMW 528i handling; steering is more precise, but it seems I'm at the wheel of a vehicle having 400 or 500 kg more than the BMW, while the difference is 100 kg only. Despite that, the 300 E is largely gaining in stability compared to the 528i; what you need to pay in pleasure, you gain in safety.
Carriage is very good for people, while the boot - even very large - is taller than deeper; this implies the smaller 528i one is more practical to carry long objects, being not so tall but very large and deep.
Climatic automatic control could be better: the six buttons on the center console do not allow you to have a mixed air flow, for example a combination of air flow to the windscreen and to the legs, which is allowed by the manual controlled air conditioning. A couple of additional buttons - one to mix upper and lower flows, one to mix lower and front flows - would get the automatic control clima equivalent to the manual one in terms of possibility.
Would you buy another car from this manufacturer? No
Review Date: 25th May, 2018
26th May 2018, 11:58
I had a 1985 Audi 80 1.8 GTE which had that problem re: not wanting to start for 5-15 minutes. Problem was the engine control relay - a hairline crack in the solder inside the relay. Once fixed, never gave problems again.
Emissions compliance unfortunately continually adds complexity to all cars. Electronics fortunately are fairly dependable, but unlike older fully-mechanical components, sensors for example are very complex yet packed into a tight package, fitted to parts of the engine which are prone to extreme heat then cold (or wet). In the old days, Mercedes could simply design a spring or diaphragm, or whatever, and simply engineer it to a more conservative design - thicker or better-grade steel, higher torque rating, whatever - and charge the cost for it, and it simply doesn't break. But sensors, for instance, don't come in several grades of "quality" - they are designed to do a purpose, and there's no such thing as a higher-grade computer chip doing a certain function, with higher quality solders, just because it's Mercedes. They are all the same. Japanese electric components fare better, I think, but even they can fail with time. Car makers can give a 20-year anti-corrosion warranty because metal, paint, wax and rustproofing can be designed to a standard. But what good is a galvanised body good for 20 years, if a sensor or assembly costs $4,500 to replace... on a car only worth $5-6K?