She lied to me (about range remaining)

[NottAM]

I am about a month into owning my S213 after 17 years with BMWs. I drove the thick end of 500 miles to Le Mans and back on a single tank of fuel, well, nearly. All the way, I was checking the remaining range and miles to travel, and there were always between 50 and 80 miles spare; I didn't think I'd need to fill up until I returned to my local fillingstation, but was ready to do so if it looked like the consumption was reducing the range.

I got within 24 miles of home, with the range showing 80; plenty, or so I thought. I'd run the BMWs down to less than 5 miles range, and Germans are all pretty accurate engineers, arent they!? Then, on a busy dual carriageway, loss of power: WTF, surely not a failure?? Then complete engine stop. Good job this thing coasts a loooong way to get to safety in a layby. Putting two and two together, lack of power must be related to lack of fuel. Got the AA out, two gallons in, and yep, she starts.

Reviewing threads on many sites, some folks seem to never get low enough to test the range displayed, and others seem to think the range is reasonably accurate. All I can conclude is that its at best inconsistent, and at worst optimistic (as in my case); surely the safe way would be to give a pessimistic range.

So now it's ME that has to play it safe and be pessimistic, 'cos Mercedes, she's a little liar! Those German engineers arent as clever or safety conscious as I had thought.

Now, is there any way to recalibrate zero on the range? I get that the absolute range is based on algorithms, and depends on load, hills and driving style, but surely when the tank is empty, thats a baseline zero, not 80 mile to go.

 

[oldguy57]

I am about a month into owning my S213 after 17 years with BMWs. I drove the thick end of 500 miles to Le Mans and back on a single tank of fuel, well, nearly. All the way, I was checking the remaining range and miles to travel, and there were always between 50 and 80 miles spare; I didn't think I'd need to fill up until I returned to my local fillingstation, but was ready to do so if it looked like the consumption was reducing the range.

I got within 24 miles of home, with the range showing 80; plenty, or so I thought. I'd run the BMWs down to less than 5 miles range, and Germans are all pretty accurate engineers, arent they!? Then, on a busy dual carriageway, loss of power: WTF, surely not a failure?? Then complete engine stop. Good job this thing coasts a loooong way to get to safety in a layby. Putting two and two together, lack of power must be related to lack of fuel. Got the AA out, two gallons in, and yep, she starts.

Reviewing threads on many sites, some folks seem to never get low enough to test the range displayed, and others seem to think the range is reasonably accurate. All I can conclude is that its at best inconsistent, and at worst optimistic (as in my case); surely the safe way would be to give a pessimistic range.

So now it's ME that has to play it safe and be pessimistic, 'cos Mercedes, she's a little liar! Those German engineers arent as clever or safety conscious as I had thought.

Now, is there any way to recalibrate zero on the range? I get that the absolute range is based on algorithms, and depends on load, hills and driving style, but surely when the tank is empty, thats a baseline zero, not 80 mile to go.

That doesn't sound very accurate does it. At least you know now that when it's showing 80 miles remaining the tank is virtually empty! What was the fuel gauge showing (if there is one?). The Focus I had decades ago was accurate to the last half mile.

 

[ALFAitalia]

I went 30 miles past zero range on my CLK 209 in the middle of the night!!......not good for the heart rate though so I would not recommend it!!
On my ALFA when it gets below 50 mile range it stops showing the range at all....just says "Restricted Cruising Range".....very helpful!!

 

[NottAM]

That doesn't sound very accurate does it. At least you know now that when it's showing 80 miles remaining the tank is virtually empty! What was the fuel gauge showing (if there is one?). The Focus I had decades ago was accurate to the last half mile.

Fuel gauge is an arc of LEDs - it was on the last one, but that is too granular to be useful. It had popped up a warning about reserve fuel at about 100 miles; but with 100 miles showing, I assumed that was just being pessimistic (as it should be), not that the two gauges were radically different. Then the range went to "--" which was another hint, but swiping the button on the steering wheel brought the display back to show "80". All that evidence led me to suspect having run out of fuel, only confirmed when it re-started after being re-fuelled.

Not exactly a "fail safe" mode of operation; had it showed LESS than the true range, I would definately have filled up; a bit like speedometers over-reading slightly, so folks don't loose their licences by speeding. Seriously surprised they let it have that much error and in the wrong direction.

 

[chic0821]

Back in the day, my Lotus Europa was very accurate. When you heard the fuel tank "imploding" slightly, it meant you had 100 yards to go until it coasted to a stop Took me about 3 sessions of this before the penny dropped. Nowadays I never let the gauge go lower than 1/4 tank

 

[esscee]

Once my fuel warning light comes on (10 lts remaining according to handbook), I allow no more than 50 mls before putting some fuel in.

 

[Fastcar155]

Hi , the fuel gauge on my car gives an indication as to the range.

 

[Bobby Dazzler]

I am about a month into owning my S213 after 17 years with BMWs. I drove the thick end of 500 miles to Le Mans and back on a single tank of fuel, well, nearly. All the way, I was checking the remaining range and miles to travel, and there were always between 50 and 80 miles spare; I didn't think I'd need to fill up until I returned to my local fillingstation, but was ready to do so if it looked like the consumption was reducing the range.

I got within 24 miles of home, with the range showing 80; plenty, or so I thought. I'd run the BMWs down to less than 5 miles range, and Germans are all pretty accurate engineers, arent they!? Then, on a busy dual carriageway, loss of power: WTF, surely not a failure?? Then complete engine stop. Good job this thing coasts a loooong way to get to safety in a layby. Putting two and two together, lack of power must be related to lack of fuel. Got the AA out, two gallons in, and yep, she starts.

Reviewing threads on many sites, some folks seem to never get low enough to test the range displayed, and others seem to think the range is reasonably accurate. All I can conclude is that its at best inconsistent, and at worst optimistic (as in my case); surely the safe way would be to give a pessimistic range.

So now it's ME that has to play it safe and be pessimistic, 'cos Mercedes, she's a little liar! Those German engineers arent as clever or safety conscious as I had thought.

Now, is there any way to recalibrate zero on the range? I get that the absolute range is based on algorithms, and depends on load, hills and driving style, but surely when the tank is empty, thats a baseline zero, not 80 mile to go.

If I’m reading that right the remaining range was 50-80 miles for the whole journey. If so then jt’s not a surprise that you eventually ran out of fuel as there must have been an issue with the fuel level reading.

 

[MikeInWimbledon]

Was the last part of the drive “inefficient” driving?

The cliche is that cruising at 50-70 gives efficient mpg, stop start: not so much.

(Seems unlikely, TBH, but the question should be asked)

 

[BTB 500]

Hi , the fuel gauge on my car gives an indication as to the range.

When the level drops below a certain point ours stop showing a range ... presumably to deter people from gambling on getting home. From memory it's about 40 miles or so on both vehicles (which are quite different; a 2007 diesel Vito and a 2019 petrol C Class).

 

[clk320x]

Lol - thought this was going to be another EV moan

 

[Bendo]

If the 213 is anything like the 212, the range remaining is pretty random and changes if you go up the slightest of hills.

My old Volvo was far more useful as it worked it out based on usage over the past 10 miles or so.

 

[grober]

Modern Mercedes cars have elaborate fuel saddle tanks due to the presence of a transmission tunnel. There are level sensors, inter-fuel transfer mechanisms and inbuilt fuel pumps leading to the possibility that the failure/malfunction of any of these systems may lead to erroneous fuel readings. The days of unitary tanks with simple fuel level monitoring are long gone!

 

[markjay]

Lol - thought this was going to be another EV moan

We EV owners call the range display gauge 'GOM' which is short for 'Guess-o-Meter'....

On the plus side, any EV owner will know that they can safely ignore the remaining miles prediction (or, as it should be called, remaining miles prophecy....), instead we mostly just look at the battery percentage and take it from there.

 

[chic0821]

We EV owners call the range display gauge 'GOM' which is short for 'Guess-o-Meter'....

Wot's an EV, is it a new kind of petrol
Regards
Luddite

 

[markjay]

Wot's an EV, is it a new kind of petrol
Regards
Luddite

It's the next stage in cars' EVolution....

 

[jasonh]

The Lexus RX has something odd like this going on too.

There is no empty on the fuel gauge, just R, which I presume means Reserve. It provides a "Cruising Range" figure which I think takes you to R.

If you work out how much fuel is in the tank at R it's 12.5 litres/ 2.75 gallons, so at 30mpg you have 82 miles left.......BUT, and this isn't in any official documentation, you MUST have 50 miles left of petrol in the tank to keep the fuel pump cool.

When the car decides to actually stop, who knows, I'm not going to try it. I imagine with the technology in it then it will stop you with remaining fuel in order to protect the fuel pump.

 

[markjay]

BTW, EV batteries degrade faster over time if frequently allowed to go below 10%. For this reason, you'd normally try not to go below 10% battery level before recharging. Obviously you can drive it down to zero % should the need arise, but you'd try not to make a habit out of it. In the OP's position, if I was driving an EV, I would plan on a charging stop (even if only a small top-up) before the battery level gets to 10%, and obviously wouldn't experience what he did.

Another interesting point is that some say that you shouldn't drive the fuel tank down to empty, unless you do this routinly, because then the fuel pump 'picks-up all the sediment from the bottom of the tank and the fuel filter gets clogged'. And: don't fill the tank when it's only half full, instead let the tank run low "to prevent crude from settling down at the bottom". I am just repeating what I heard, but personally I believe that neither is true because the fuel in the tank gets sloshed about while driving. But who knows!

 

[TC350]

Many years ago I was working for a car dealer when I took a trade-in Ford Mondeo from the garage to our storage area about 5 miles away along the M3. Like most cars within the trade it was low on fuel, but showing a range of 30 miles. Knowing it would just be put into auction, I didn’t bother putting in any fuel before setting off. Whilst in the middle of roadworks on the M3 it coughed and spluttered so I pulled over onto the hard shoulder, which was being used as a live lane. The car was still showing a range of 27 miles.

While sitting up on the embankment it was interesting to note the number of vehicles that couldn’t see the abandoned Mondeo with its hazards flashing away. They either swerved out at the last second or ground to a stop behind. It took about an hour for a colleague to get to me with a can of fuel through the traffic jam I’d caused. I’ve never relied on range guesstimates since.

 

[markjay]

..While sitting up on the embankment it was interesting to note the number of vehicles that couldn’t see the abandoned Mondeo with its hazards flashing away. They either swerved out at the last second or ground to a stop behind. It took about an hour for a colleague to get to me with a can of fuel through the traffic jam I’d caused. I’ve never relied on range guesstimates since.

There aren't that many cars braking down on the hard shoulder, and you'd think that the probability of another vehicle careering off the main road at that precise location must be very small, i.e. "it's just bad luck".

But these accidents are not a coincidence. What happens is that after driving for a long time drivers just get used to driving behind the car in front of them. And, on longer journeys, drivers relax and let their peripheral vision do most of the work (even more so if the driver is distracting by their phone or satnav or radio or just reaching for a snack etc). Under these circumstances, the driver will subconsciously turn the wheel to follow the (stationery) car in front of them, thinking they're driving in a convoy. This in fact makes cars parked on the hard shoulder a 'magnet' for trailing vehicles. The hazard indicators are just not powerful enough in daylight to attract attention when drivers use their peripheral vision.

On a positive note, this should become less of an issue in years to come, because more cars have collision avoidance radar and cameras these days, including automatic braking.