Smart Fortwo cdiSmart has pulled the ultra-economical Fortwo cdi from the UK – despite it being both one of the most fuel efficient cars on sale and a multiple MPG Marathon champion.

The diesel range has been withdrawn from the UK in preparation for the new Smart model: petrol models do remain on sale, though.

Indeed, it’s the petrol Smart’s sheer popularity over the diesel that has seen the firm drop diesel from the UK. A £1,200 price premium for diesel over the base 71hp 1.0-litre petrol engine is certainly a factor here.

The diesel may have averaged 85.6mpg, but the mhd petrol cars still do 67.3mpg. Factor in the extra cost of diesel over petrol and, if you cover 10,000 miles a year, you’ve a fuel bill of £734 for diesel, and £881 for petrol.

It would take buyers more than eight years to recoup the price difference at that heady mileage. And, of course, most Smart drivers didn’t cover anything like that a year…

Add in its gruff nature and extreme lethargy in practice, that would contrast sorely with a petrol car on a dealer test drive, and the reasons for the car’s demise are clear. In this case, for all its economy records, diesel simply didn’t add up.

Given this slow-selling experiment, plus the fact key city car rivals don’t offer diesel variants, will there be an ultra-eco champ version of the next Smart? All will be clear at Paris Motor Show 2014 when the all-new one is revealed…