Pain in the arse things DPF's, on my car i have one, the earleir model
has the exact same engine, just minus the DPF, as a result my car
struggles to do more than 75mpg (of an 85 claimed by the dealer, i
usually see 68 - 73mpg..... 75mpg was attained on a long run in germany)
The earlier models did 85 - 95mpg no probs, and quite often would just
nudge the 100mpg barrier,

Putting your implausible mpg figures aside, pouring more fuel in via the
main injectors is "old school" and newer cars have a bespoke injector just
upstream of the DPF which removes the risk of engine oil contamination.

Why implausible??
i get between 68 and 73mpg... calculated on fuel to fill up and miles
covered since last fill, that's a mix of driving, some round town to the
shops, some 20 mile round trips at 30 to 50mph on the ring road, plus either
a 45 mile round trip down the M1, or a 80 mile round trip along the A52
twice a week,
but i do just tootle along at 70 on the motorways,
the engine is only 800cc's mind, and 3 cylinders, and the whole car weighs
780 kilo's empty, so i imagine that helps,

the dpf on this engine starts a couple of inches after the turbo, so maybe
not much room for an exhaust injector, but yes a dedicated dpf burn off
injector in the exhaust would be nice, instead merc decided to use the 'fire
the main injectors on the exhaust stroke' trick instead,

I don't know where you buy your non-biodiesel. By EU law, all diesel
contains 7% biodiesel and has done so for several years now I believe.

Meh, bit of a difference between 7% and 100% tho,
last month i filled up in France, Belgium and Germany, so i wonder if any of
those still sells the full sulphur diesel, couldent tell ant performance
difference, but then again for more than half the trip i had 150 kilo's of
train and bus parts in the boot and cycle rack mounted back box...

was going to take the trailer, but the euro drain wanted double the solo car
rate, which is the same rate for upto 6 meter long cars,
my car is 2.6 meters long, plus a 2 meter trailer inc drawbar, so both
together are still shorter than most cars,

Still, it was nice to be able to use the free short car parking spaces in
Germany, but now we're really off topic.