I have a 07 BLT vRS SE which recently had a full service and remap. The garage provided a Pipercross filter but they could not supply at the time of servicing and sent it out in the post to fit myself.

Prior to the service and remap the car computer indicated and average mpg in the range of 55-65mpg at the end of 200 miles per day split between 40% long runs and the rest urban travel. I always assumed that the computer was being optimistic but not wildly so. Immediately after the service and remap I was amazed at the improved drive of the car and made good use of the extra performance on offer. A couple of weeks after the remap, when the novelty had ore off somewhat, the car was consistently returning 44-48 mpg at the end of a days travel - much more in line with what I would consider to be realistic given the engine size and journey types. I was a little disappointed however since I thought a remap could improve mpg (I may however still have been using the performance of the remap and just not realising!). First question - does a remap (Unit 18 in this case) reset or change the way the car calculates mpg?

Anyway - when the remap was done they knew I was having a performance filter fitted (mike made a point of asking) so could the map have not been operating optimally on the original (since new!) filter that was in the car? There was (and still is) zero diesel smoke at any time so I guess it was getting enough air for full combustion(?).

Anyway, I have now fitted the filter and it has been in for about 5 days now. Since putting in the filter the mpg has increased significantly (as indicated) to between 58-64mpg at the end of a full day. Is this due to the map being able to get the air it is now mapped to 'expect'? Or is this just coincidence or is it perhaps just my driving style adjusting to the cars characteristics and me not exploring the rev range so much any more resulting in better economy?

Just a note on changes noticed from the panel (if anyone else is thinking of getting one on a mapped car) from my experience - the car just feels less 'strained' at all times. The car sounds and revs smoother at higher revs, throttle response seems improved and I swear the turbo sounds slightly louder. I got the panel for a very good price and for the price I paid I think the subjective changes are worth it. If the mpg changes are real and directly attributable to the panel then it is DEFINATELY worth getting a performance filter. If the gains are not from the panel then I think the other subjective benefits (i.e. benefits I have noticed but could not quantify in any way) are not worth the outlay of the panel - it would probably be easier to just replace the oem paper filter either as per schedule or more often if desired. Just my thoughts.

Anyway, I hope someone can answer my mpg queries above as if the gains really are from the panel (and perhaps from the remap taking advantage of it) then a performance panel filter really is a must do 'mod' as an extra (minimum of)5-10 mpg is nothing to be sniffed at imo.

One other quick question - has anyone running a unit 18 map (or other comparable map) got any experience of running both regular diesel and their alternative performance fuel (e.g. BP Regular vs Ultimate, or Shell Fuelsave vs Ultimate). Are there any gains or benefits that have been noticed or is it not really worth the outlay? I personally never really noticed any gains other than perhaps piece of mind in knowing that the injectors etc were being maintained or even being cleaned etc. I never noticed any performance or mpg gains but I did notice less diesel smoke on the original map (the remap has zero smoke on normal fuel - I have not tried performance fuel yet). I just wanted to hear peoples opinions as I don't see the point in spending extra £££ per tank for no real benefit when I can just get the fuel system cleaned at servicing time if needed.

Thanks for any advice or info you can offer.

Steve

You can do an 'adaption' using VCDS to alter the fuel economy reading. It's in instruments. It's possible that the calibration has got a bit out of kilter when they remapped the ecu. Just a guess.

I've tried V-Power Diesel and normal Diesel in my company car (Audi A4 2.0 tdi quattro). I get about 1 and a bit more mpg from the V-Power, and iirc it cost about 1p extra per mile to run.

It definitely felt smoother, quieter and more 'willing' though.

Just looked up the fuel figures. As an example V-Power cost 16.3 pence per mile, and Diesel was 15.6 ppm. So over a whole tank that's about £3.50 extra.

But you do get more plus points for V-Power as well...

First question - does a remap (Unit 18 in this case) reset or change the way the car calculates mpg?

Yes, you are likely to have 'lost' the ECU calibration.

...zero diesel smoke at any time so I guess it was getting enough air for full combustion(?).

Yes, it's the turbo shoving the air in, not the atmosphere.

...just my driving style adjusting to the cars characteristics and me not exploring the rev range so much any more resulting in better economy?

Absolutely.

...it would probably be easier to just replace the oem paper filter either as per schedule or more often if desired. Just my thoughts.

Of course it would and you'll have MUCH better filtration which after all is the air filters sole purpose.

...are there any gains or benefits that have been noticed or is it not really worth the outlay?

Not really, the posh petrol is worth it because you're getting a higher octane rating, but the diesel is still just diesel with extra cleaning agents in it.

You are risking premature damage to your turbo and possibly MAF by fitting a poor quality filter.

The manufacturers of this rubbish don't care either, they simply want your money, the profit margin on 'performance' filters is fantastic for both the manufacturer and the reseller. In practice you would find it impossible to prove that the fitment of such an item caused premature damage to your turbo and they're banking on that, you would certainly invalidate any warranty you may have on the basis that a different filter had been fitted.

Edited 7 September, 201114 yr by sepulchrave