Owner suggestions on buying an 2014 B -ED

B-Class Electric Drive Forum

Help Support B-Class Electric Drive Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.


New member
May 31, 2019
Hello everyone,
I'm new here. I recently found out this forum and read some topics. I'm in the decision process for buying a used 2014 model B class. I have 2 ICE cars that will be third one. I plan to drive it in-city or short distances.(<40 miles round trip)

The question
The forum topic about changing Drive Unit replacement worried me and I put my decision of buying on hold. It's mentioned in Drive Unit replaced topic here (http://www.mybclasselectricdrive.com/forum/viewtopic.php?f=8&t=1172) that cooling fluid leak is a problem for 2014 B-classes especially over 40K miles.
I wonder if it's the case for every 2014 B -Class? Especially around 52 K miles.

The vehicle I'm planning to purchase is well priced. fairly used with >50K miles. Carfax says it's towed once while it's in 41K miles but it doesn't say Drive unit change/or failure. Only a mechanical failure was recorded. The car will not have any warranty on it. (Even if dealer may say 30 days warranty but it may not include Drive unit changes)
The dealer is not a MB dealer and they want to get rid of the car by selling it. (As price suggests)

I tested the car.It had an unusual sound while driving. I can't tell it's the pedestrian warning sound or sound coming from the drive unit. (the dealer suggested it's a tire balance issue)

I ask for your opinion and comments on what you would do in this case.
Is there a tell sign of cooler fluid in drive unit. What should I check /have the car checked to identify very expensive problems?

Battery seems to be degraded in acceptable way. It may have 60 miles of charge on regular and I'm ok with it.

Thanks in advance and cheers.
Make sure it has the range extender option. It was stock in 2015 plus cars but it was an option in 2014. I purchased the only one out of ten cars with it.

I would suggest you take it into the local MB dealer and have them plug into their computer and do all the standard tests.

A small fraction of Tesla motors failed but the question remains why it was towed. Are there no service records available?

Never trust anything a car salesman tells you.

The pedestrian hum is only heard outside the car. If you test drove the car, it should sound like a pleasant spooling up hum and not very loud. A high pitch whine could mean the motor is on its way to failure.

When fully charged in warm temperatures, the range meter should be reading 85 miles without range extender. If down in 60s, the battery has degraded more than usual. The dealer will know if the annual battery inspection has been done and what it shows.

All that being said, I would pass unless an authorized MB dealer has plugged in and run the basic tests.
It has the range extender version. (The button on center console)

I didn't see the car fully charged, it was showing 29 miles on 50% and 16 miles on 25%.
The sound I hear during the test drive was not a hum for sure. It was changing with the speed.(like something is lightly clunking) maybe it was the brakes. It was loud enough to hear while windows closed.
I didn't hear that sound over 40 MPH.

Thanks again. I think I'll search more available cars.
Two more thoughts... first, my 2014 still had a little of the M-B warranty left on it when I bought. Several things like rear struts were replaced for free under warranty.

Also, when I found my car on the lot in January, it also said 62 miles range. Someone on this forum suggested I reset the display (under E-Cell I think) which erased the previous driver's habits from the equation. That immediately improved the range estimate. I think it bumped up into the 70's. This was in a chilly January, since then on days in the 70's I have seen as high as 100 on the guess-o-meter, and I do not have the range extender.

But these cars are not in short supply if you don't mind buying site unseen and shipping charges, so perhaps wise to move on, or as suggested let your local M-B dealer give it a once-over.
Our 2015 B Class electric also experienced a leaky drive unit and our dealer fixed it (not replaced) under warranty about 2 years ago. We never noticed anything wrong with the drive unit, but the dealer mechanic spotted the issue during a 20K service. So assuming your dealer is experienced with B class electrics, it would be worthwhile to have them look at the car prior to purchase. Otherwise, our B class hasn't experienced any major issues so far (albeit we only have about 34K miles on our car).

The only other bummer worth mentioning is that Mercedes has taken down any ability to monitor charging remotely (as of May 31, 2019). Very handy when you are plugging in at a commercial location and want to move the car once it is charged to say 80-100% out of courtesy for other EV users who need to charge. Very disappointing. You can however monitor through another 3rd party charging app via EVGo or Chargepoint.