Fuel Economy/Engine Treatments

[sloblock_uk]

I'm aware that alleged fuel economy has been the subject of mockery and cynicism in the past but I thought I'd tell you about my own experience using an engine treatment I tried in my 940S saloon. It's a J-reg 138,500 miler with the B200F engine. Previously, I'd estimated the fuel economy at roughly 25mpg.

As per the instructions, I filled up the tank and put in a bottle of Petrol Magic (£6.00) after seeing it advertised in a magazine. It's a once-only treatment that claims to clean the engine's injectors which results in a power and economy boost and a reduction in emissions. Once that had run through I decided to actually see what difference, if any, it had made.

Into an empty tank (the fuel warning light had only just illuminated), I put in £15 of unleaded petrol (it was all I had in my pocket).

£15.0 at 82.9p per litre = 18.1 litres

18.1 litres = 4.0 gallons

I then covered 126 miles before the fuel warning light illuminated again. My commute consists of a 10 miles through the city, then 53 miles of undulating motorway at 70-75mph and the reverse when going home. My driving style varied from "keen" around town to "relaxed cruising" on the motorway.

31.7mpg

I can't say I noticed a big difference in performance, perhaps throttle response is a little bit better - but that is a marked improvement in economy, don't care what anybody thinks.

I think, for an old 2.0 motor weighing the best part of 2 tonnes, 31.7mpg really is not too bad. I was considering saying goodbye to the old girl on the grounds that I thought she was too thirsty but I might just hang on to her for a bit longer now.

Anyone used this product - or think I'm talking b*ll*cks?

[Clifford Pope]

I think these products that clean injectors really do work, if the injectors were a bit gummed to start with, but I also think there are other factors at work:
1) It is worth cleaning out the flame trap, throttle body, idle air valve, and inlet system generally. These are in my experience much more in need of regular attention than the injectors
2) People often fail to do a proper mpg monitoring before the start of the experiment, so any benefit tends to be exaggerated in the mind. eg you say fuel consumption was estimated at "about 25 mpg" You really need to have been keeping detailed full/full records over some time before comparison with your first set of figures after the treatment can give any significant conclusions
3) It is human nature to try especially carefully to drive in an economical way while monitoring the result of such experiments. There is a natural wish to want the experiment to suceed, so one tends to act subconciously to make it succeed.

FWIW I get a consistent 32.something mpg from my B200F 240, 1993 with 320,000 miles. It improves to 35 on a careful long run. I know from experience and recording of every tankful that when it falls off a bit, say to 31 or even 30, it means the Throttle Body etc are due for a clean again.