So much misinformation in this thread, but I am still keeping out

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Yes, that is my opinion. I have driven many turbo diesels, and a few naturally aspirated diesels. I have had a turbo diesel Passat (red badge, A6 engine) and a diesel LR Discovery. Class 3 driver's license (unlimited GVW on highway, with air brake endorsement, meaning almost exclusively diesel.

I also worked in the diesel engine industry (engineering, sales, service) for 26 years. 15 to 8000 hp.

Diesels inherently have no effective engine retardation other than friction. That is simply because while they have a higher compression ratio, they are not throttled. When the air in the cylinder is compressed, it is then decompressed, for no net work, thus no retardation. If you want to have retardation (which occurs naturally with a throttled gasoline engine) you need to include an exhaust brake of some type, Jake or otherwise. That is why those devices were designed. That device opens an exhaust valve after the compression stroke, releasing the compressed air (and making lots of noise). There are also hydraulic retarders. All designed to overcome the limitation of the diesel engine with respect to lack of engine retardation.

If you want to learn more about diesel engines and their development, and the challenges faces (including lack of engine braking) suggest you read Cruickshank's book on the Cummins engine company and the engineering development of the diesel engine concept over 75 years.

I am glad you like your diesel engine. But please don't spread so much piffle. It makes you look like a w**ker.

^^^ As much as i agree with you on the retardation,my X5D's engine has more braking effect than any of my other cars,4.6is included.I dont have accelerometer in this car,but it will be interesting to have the decel values measured.

Diesels are fine in stop and go driving, they are just better in constant load applications. Best way to achieve that steady load factor with stop and go driving is to use some form of hybrid IMO.

All internal combustion engines are 'compression based', but diesels use compression ignition. Careful on your warm up comments, as you need sufficient preheating to start, but then the engine warm up cycle is just the same as a spark ignition engine. Do not idle it, wait until you have oil pressure and drive as soon as possible, at low to moderate loads. Engine warm up happens faster with some load applied.

I don't know if BMW has included any sort of throttling mechanism to enable that retardation. Would be interesting. I suspect they wouldn't, since they have gone one step further in the latest models and moved to a freewheeling feature. Now that would blow for towing significant loads.

Agree that the diesel cycle is inherently efficient.

You don't have to go to a CRV to compete, though. The best way is to reduce vehicle weight. Our 2007 X3 3.0si (265 hp IIRC) regularly does 32 mpg (imperial)/26 mpg (US) on the highway. It drops closer to 28 mpg (imperial)/24 mpg (US) in mixed driving, and if I did pure city driving I am sure it would drop further. I drive efficiently, but make sure to use a good portion of the 7000 rpm limit regularly.

My first car was East German "Wartburg"-3 cylinder 2 cycle engine with a freewheeling feature on the transmission,so nothing new under the sun ;)
Actually that car was made after WWII until mid 90s in the ex-BMW factory in Eisenach,so my first car has at least BMW spirit :D
I have read all the documentation about M57 engine and didnt see anything mentioned for throttling under no-load,but it may be just a side affect of the EGR system function.There is a throttle body in the intake tract.

Come on, jump in, you know you want to.

I drove an early SAAB 99. They also used a freewheeling feature. Don't know much about the Wartburg, but I did know about DKW 2 stroke models built in the same time frame, and I see that there is some common parentage there as well. Small world.

Yes,I think the engine was copy of DKW 3 cylinder,one with the radiator installed behind the engine.