Can I Improve Motorway Mpg With K&n Air Filter For Rx300?

[RobinGBrown]

Every year we drive to Slovakia in our RX for summer holidays. Last year, by waxing and polishing the car, I managed to get 27.4mpg on the motorway.

This year I'd like to improve it a bit more so I was thinking of ways to accomplish this and one thought was to fit a K&N filter. I have one in my Honda Accord coupe and that seems to do better with it.

Has anyone fitted a K&N filter and noticed what effects it has on the RX? Does anyone have any other ideas for improving motorway mpg other than switching off the aircon?

Thanks

[Boxbrownie]

Raise the tyre pressure to the maximum allowed for fully loaded, the ride will suffer but economy will improve, don't drive with the sunroof/windows open on motorways or above approx 40mph and if possible turn the AC off when not needed.

You could try an oil change and use an oil of the correct spec but intended for fuel economy, but if an oil change is not scheduled its doubtful if the outlay will warrant the return in one journey.

[RobinGBrown]

I usually get it serviced about a month before we go so it will have fresh oil. When I bought it the previous owner was running the tyres at 35 psi and they were worn down in the middle, 32 is the recommended pressure which I've left it at. Hard to know which is better save on tyres or save on petrol...

Its approximately a 2000 mile round journey so improving the mpg does have an effect.

[Boxbrownie]

Indeed it is, but if the car is fairly loaded for the trip anyway you may need to increase pressures regardless? One of the biggest improvements to fuel economy is the tyres anyway, when it comes to change buy a premium set with the emphasis on economy, something like the Goodyear Efficient Grip, my son changed his Michelins for these on his BMW and on the run to Uni he now gets around 55mpg as different from the 46 mpg he used to get, nothing else had changed not even the weather (at first).

[IHgs300]

After reading your first post, I'm sorry but i find it hard to believe that washing and polishing the car has any effect on MPG. Was it covered in a lot mud or anything?

Not being picky just a genuine interest.

[Boxbrownie]

After reading your first post, I'm sorry but i find it hard to believe that washing and polishing the car has any effect on MPG. Was it covered in a lot mud or anything?

Not being picky just a genuine interest.

I remember a long time ago I was working at RAF Alconbury (it was a USAF base at the time) when a Vulcan made a rest stop (to visit the on base facilities provided by the Yanks, cheap shopping etc ) , the US ground crew were amazed when the crew of the Vulcan before whizzing off for thier shopping expidition got out the mops and brushes and started cleaning down the wings.....BIG wings! Apparently a clean Vulcan went a helluva lot faster and used a lot less fuel when spotless.........OK so a dirty RX is slightly different but it all counts :D

[rayaans]

Raise the tyre pressure to the maximum allowed for fully loaded, the ride will suffer but economy will improve, don't drive with the sunroof/windows open on motorways or above approx 40mph and if possible turn the AC off when not needed.

You could try an oil change and use an oil of the correct spec but intended for fuel economy, but if an oil change is not scheduled its doubtful if the outlay will warrant the return in one journey.

Raising tyre pressure is a very good one. I think its called hypermiling! It definitely does work. Low rolling resistance tyres help too

[Boxbrownie]

Yes indeed, and a few manufacturers have an "economy" setting for the tyres fitted alnong with normal pressures in the manual and fuel filler flap/A pillar notification.

[v3ttrx4h]

Has anyone actually fitted a K&N Filter and noticed any difference to performance/economy?

[It wasn't me]

They generally won't make much difference if any at all , cone filters will give u cooler, so denser air which will aid combustion.

They do increase air flow, due to the filter being less restrictive, but this will only really works on high powered performance cars but It will however filter out even smaller particles than standard paper elements.

[Boxbrownie]

Also to note that most OEM filters nowadays are cotton material and not paper, hence the longer service intervals. Some of the cheaper cost cutting manufacturers will still use them but I know I bought a replcement air filter for my RX a few weeks ago from ECP and it was a cotton type.

The K&N filters are oil impregnated which may aid filtration of smaller particles but then again are you running a car or a operationg theatre?

[stevet]

Some also say the oil impregnated ones can coat the very sensitive air flow meters with oil and cause problems.

[It wasn't me]

I agree, Japanese and Korean manufactures use cotton but European manufactures the likes of the (german and French) use paper.

You never know Boxbrownie, for all we know Robin might have OCD,after all he's does like a clean highly polished car, (which will aid fuel consumption slightly) less drag,in which case he might also like a finer filter, every little bit helps!.

[Boxbrownie]

Some also say the oil impregnated ones can coat the very sensitive air flow meters with oil and cause problems.

Although K&N (surprisingly) say thier tests reveal no such deposits are detectable upon correct application of the oil.......but I wouldn't use one, OEM are fine.

Not all Euro makers use paper.......I have several Fiesta cotton filters on the shelf in my garage, and thats a cheapy in the range