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The 10 diesels with the worst Real MPG fuel economy

Contrary to popular belief, diesel cars will not automatically deliver outstanding fuel economy. Far from it, according to the latest Real MPG submissions, some popular diesel will need to cover millions of miles before they pay off their costly premium.

Here are 10 of the worst diesels for real world economy. We’ve obtained this list by using our fuel calculator to calculate how many miles you’d need to travel before the premium for diesel pays itself off compared to the petrol - both figures are taken from Real MPG. The comparison is between cars in the same trim level but please note that these numbers do not take into consideration other costs, like servicing or annual VED. 

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BMW 3 Series Touring 320d xDrive Sport Auto

38,240,634 miles to break even

That’s right. You’ll need to cover more than 38,000,000 miles in your diesel 3 Series estate before it’ll recoup its initial extra cost of £3110. According to Real MPG, the 3 Series Touring 320d xDrive Sport Auto misses its advertised economy by 15mpg and this means you get a paltry £1 annual saving, compared to the 320i.

Click to see BMW's Real MPG


Robert Fonis    on 22 November 2017

Hmmm...5 of the 10 are VW Group vehicles. 7 of the 10 are German. Really need to hand it to the marketing departments of VW, BMW & Mercedes!!!

symonh    on 22 November 2017

Are these based on real world petrol MPG figures or Manufacturers ones?

SteveTTT    on 22 November 2017

Sorry guys, you seem to be highlighting the diesel mpg shortfall, but not that of the equivalent petrol model. So while I don’t question your stats it’s not possible make a real comparison between the two fuels, unless I’ve misread the article?

Edited by SteveTTT on 22/11/2017 at 21:26

Chris Baker    on 23 November 2017

When i read this in the introduction 'We’ve obtained this list by using our fuel calculator to work out how many miles you’d need to travel before the premium for diesel pays itself off compared to the petrol. The comparison is between cars in the same trim level. '

It appears to suggest that the equivalent petrol and diesel models have been compared (incl. real world driving mpg).

Trevor G Jones    on 22 November 2017

Not sure why these diesels clock up such poor mileage. My wife has a diesel Zafira she has had from new in January 2004, it has 130,000 miles behind it. It does a regular 50/51 everyday driving from shopping, an eight mile trip to 170 mile round trip to see her mother. Meanwhile our VW T5 diesel Camper does an overall 40/41 m.p.g. although this is mainly on journeys from 22 miles to maybe a 1,000 mile five day trip away. I always drive on the rev counter as I used to do competition motoring years ago. A vehicle I had previously was a 1999 Skoda Felicia top of the range model with the 1600 Golf petrol engine, that did around 42 m.p.g. around town to 57 m.p.g. on long distance running. So I cannot understand how people get such poor mileage with these diesels unless they drive them flat out up the motorway.

Husbandofstinky    on 23 November 2017

Absolutely ridiculous article fueled (sorry for the pun) by poor data usage. Sorry Dan Powell.

Example 1:

The worse culprit apparently:

BMW 320d xdrive auto - 45.5mpg

BMW 320i xdrive auto - 44.6mpg

Really???? Theoretically possible but as HJ point out 102% over manufacturers figures. So is this a sample of 'one' who posts daft data or records it under the wrong vehicle?

I could relate to the diesel (auto plus 4WD would zap the figures). Stock non 4WD shows 48.9mpg

However to highlight the poor data, moving down to BMW 320 auto, this states 36.4mpg. Still quite respectable but more realistic.

So using HJ's data

Non 4wd auto 320 petrol owners should buy an xdrive because they will achieve a 22.5% increase in fuel efficiency over the stock 2wd version..... BMW's own figures show that 4wd is less efficient than 2wd (we already know that of course) by about 10%

So HJ please asses the data properly before jumping on the anti diesel led band wagon posting spurious claims using very dodgy data indeed.

Realistically it should've been:

BMW 320i auto - 36.4mpg

BMW 320d auto - 48.9mpg

But then of course it wouldn't have generated the Daily Maileseque type article....

I have a huge amount of respect for the whole HJ site, all those involved and spend a lot of time here reading articles and Q & A's. I have recommended it too to many but this article should not have been released without some more diligence.

tomsdad    on 23 November 2017

Here's a different view I love driving my 2 litre 308 HDI auto because of the of the instant torque, you are never left with no instant power just put your foot down and its there very safe for overtaking.
Not a high mileage user 48 MPG will do me.

HairyJones    on 27 November 2017

Amazing the worst culprits here dominated by VW Group cars again. Another Diesel-gate in the making?

Richard Piers    on 28 November 2017

Many years ago bought a 330d small mileage ex BMW staff car. The dealer tried to persuade me the petrol version was equally parsimonious.
Few weeks later drove to Italy, filled up in Le Havre at 0730, one top up en route small quick lunch, tour around Chamonix for a look see and was in the centre of Milan at 1630 having sat at about 100 mph all the way and did 42mpg. No way in the world a petrol car would have got even close.
When we sold we got a premium. Due to stupid and inaccurate articles like this plus the largely extravagant bad press second hand values may currently be down. Good time to buy !

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