Last week, someone did this to my car whilst it was parked on my road:

Then, as a direct result, this happened two days ago:

Now, I am getting 8mpg more on the motorway, and 5mpg more around London... I guess it's because of the increased airflow over the intercooler.

Which begs the question, do you really need an arch liner on a cheap, galvanised, heavily-undersealed car?

Think it is to protect from flying debris more than anything else

one hell of a way to do a Pikey mod

Yep, a stone through the intercooler wouldn't be good.

surely some fine chicken wire would do the trick? what a great way to increase fuel economy

Yeah - I'll eat my fist if a stone makes it through the intercooler. Got more chance of it coming through the front...

I think my next arch liner (I will replace it, as I notice now that the power-steering belt is pretty exposed to debris flying-off the wheel) will be swiss-cheesed with a large drill bit, a-la the common airbox mod on Mk2 Golf GTIs.

Chris - might be worth also noting that I pulled the funnel thingy off the front as well. I don't know if this makes any difference.

yes the funnel thingy :confused:

The bacl plastic bit that channels air into the IC.

Put everthing back together this evening and took a trip into London. Swiss-cheesed the replacement arch-liner before refitting... 34mpg with aggressive driving, which a touch better than it was.

Also replaced the MAF and it feels like a different car (brutal). Guess it's woken the remap up again...