I have had my BMW 525D terracleaned, she is on 140000 miles. what a difference after, emissions were halved, fuel economy is up by 4mpg on average, the engine is so much quieter and the power delivery is alot smoother. This was done about 6 months ago and my fuel economy is still 4 mpg better.
The chap that did it (Clarkeys Autos, Highworth Nr Swindon) said it is alot more beneficial on diesel engines than petrol because they produce more carbon deposits. treatment took and hour, I was delighted with the results, only cost £70, so will i get the Alfa terracleaned? the answer is definately especially as recently it seems to only be doing shorter runs (never good on a diesel) I just need to find some time to book her in