Yes - used it in the Peugeot (BG244 is the diesel variant, although I expect the similarities outweigh the differences). Not that it had a coking problem but I like to assess some of these products.
NB - I NEVER use OIL ADDITIVES, flushing agents are probably OK but I AVOID all others.
For an engine with no problems anyway I'm not sure why I tried it, but I did. And no harm was caused.
I have also run it through the BMW in Feb 2011 (the BG44K for petrol engines this time) simply because it had been a low mileage car for its age when I bought it - such cars often coke up more than ones that are driven harder and for longer. In this case it did quieten down the engine under hard acceleration, not that it was noisy anyway but it did seem a little bit sweeter after treatment. The CO also came down from 0.05 to 0.012 afterwards. So, perhaps it does work?
What I am presenting is very subjective opinions - with a badly coked up car I imagine that the results would be more spectacular. Or perhaps not noticeable - perhaps it doesn't work after all. All I can offer in defence is that I'm a very sensitive driver and notice tiny changes in a car's performance or handling. Then again, perhaps I EXPECT to notice a difference because I know I'm a sensitive driver.
The primary active ingredient of the BG products is polyetheramine, which is acknowledged to be very effective at removing carbon deposits. It's the same stuff that fuel companies add to their fuel as part of the retail additive package for forecourt fuels. But it's in MUCH higher concentration as a consumer additive.
Lexus reportedly uses this stuff at every service.
Not a good reply really, is this? I am not a biochemist but I can't see how it would do any harm.
You pays yer money, and, heck, well, you know the rest, don't ya?