Here in Holland I can choose between the regular diesels (Shell low sulphur or BP 'cleaner diesel' as they call it.
The new ones are called Shell V-power and BP Ultimate. I know for sure that Shell uses a different name in the UK, but I'm assuming that the 'new' diesels have the same special ingredients.
I've been running my Tdi on V-Power mostly, sometimes alternating to BP Ultimate but always a new diesel. And that for at least the last 5000km or so.
Bottom line: I'm not impressed, except for the price
I see absolutely no gain in power. My Tdi has been chiptuned by ABT, giving me about 95 bhp, but I just cannot feel a difference.
I might see some improvement in my fuel consumption, but I'm a real split-personality once on the road, so there are times I can do 60mph for ages and sometimes I go raging around like a loose bull. But a fact is: I've reached the highest nr of km per tankfull when running V-Power/Ultimate.
I think that my observation is more or less in line with what I've read on the internet. Scientific approaches see anything between 1 to 3% performance gain. Not enough to be noticed.
So why do I go on using it?
Because my boss is paying, largely (the advantage of a company car). Because it might be better for the environment and my engine. Because it could give me a psychological hp gain. Because I want to know for sure.
Finally, as for which one is the best: I seem to prefer Shell V-Power (because of seemingly better mpg). But I read that, on paper, the BP stuff should give more hp gain.
Just my 2 cents!
Edo
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(2003 Silver 1.4 Tdi Exclusive(SE), 95bhp/235Nm chiptuned by ABT, black interior, sport seats, heated mirrors, TomTom3 PDA Satnav, JVC KD-SH909RB cd-receiver, Infinity Kappa 63.1 + Vifa on-dash tweeters, 12" Subwoofer on 300w Amp)