[G33]

Guys

Everytime sum1 posts about a remap they always mention improved MPG as an advantage together with greater perfromance kinda like a win win situation! Inevitably a remap with the power increase will obviously decrease MPG when giving it the beans...burning more juice etc. What i dont understand is how we/they manage to get better MPG from a remap. Surely car manufacturers who spend millions in development could have done this straight off boasting better MPG figures?!? On the flip side I understand why the manufacturers dont give us remap power due to longevity of mechnical parts, warranty etc. but surely the added MPG from a remap 'map' can be accomodated under a stock ECU map?!

Hope that makes sense, just found it intriguing

[beemerbird]

Can't comment on the petrol variants and re-maps but as far as the diesels go then yes mpg is improved post re-map during 'normal' driving. You're right though, give it some and the mpg will be slightly worse than before the re-map. My E92 335d we're only talking about 2-3 mpg worse, so overall there still was an improvement.

I also agree that the manufacturers could simply provide this state of tune from the factory but again, as you say it could possibly compromise reliabilty et al. Also the engines are designed for a global market and the fuel that may be used. Not all fuels are of the same quality depending upon the country. We are ok here as our fuel is the 'good stuff'.

Sure Tony will give a good explanation as to the re-maps of the petrol engines.

[E92Fan]

The thing with remaps on turbo-engined cars is that they generally give a big bump in torque figures. Under normal driving conditions, the engine will ride the greater torque curve, requiring less kickdown or outright power to maintain speed. Driven carefully, this can and generally does lead to an improvement in MPG.

However, when really pressing on, the MPG will drop far below what was previously normal as there is a much higher fuelling rate in order to develop the increase in power.

And yes, manufacturers can give this power from the factory, but normally it's against their commercial interests to do so. More importantly the engines in particular need to be reined back so that they fall within acceptable boundaries of long-term reliability (ie. the manufacturers don't want to go skint by constantly fixing engines!).

[doughboy]

You don't get more power for nothing! Use it and you'll use more fuel - that's physics. Keep it down though and as E92fan says you can benefit from improved efficiency at lower revs.

But you can FORCE economy with clever mapping.....

My brother, via some US contacts, is working on industrial scale ECU mods for a couple of large UK delivery companies using transits / sprinters etc.

He is trialling / selling them remaps for fleets of vans, basically to stop nobhead drivers thrashing the arse of the motors. The fuel and servicing and insurance savings will run into millions of pounds per year by limiting speed & revs whilst still giving driveability at full load. They're running a 3 month trial on 50 vans now.

Large fleet operators buy vehicles en-masse without extended warranties ayway so they're only interested in savings on running costs.

Watch out for a delivery driver doing (exactly) 56mph near you soon!

[MEGA]

Lowest I'd had my 320d before the remap: 17mpg.

Lowest since the remap: 7mpg.

To achieve that, I was riding 2k rpm in second gear, with traction control off, sliding around cornes of a private estate. But no matter what I tried to do before the map, 17 was the impossible boundary.

so it sure makes a big difference.

However day to day driving, other than when I'm feeling very spirited, its definitely improved. My mentality is slowly changing, and accepting that I have the torque in 4th, and don't need to sit in third. I don't kick down, and all in all, the mpg is good.

Would recommend it to anyone.

[PhilR]

Initially i found that MPG did improve slightly (1 - 2 MPG)

However after a short while my MPG did drop but purely down to the fact that my right foot became heavier post map as I began to enjoy the extra thrust

I can achieve the same MPG as I did pre map if I am a good boy and try hard.

[rogerxp]

Don't forget the engines get tuned up slightly for most face-life cars. The engine is the same but every couple of years it gets tweaked for better performance & mpg. This had happened with all BMWs engines.

BMW & Audi play the same game. You'll notice each face-life just out does the competitions current offering, it isn't long until the competition brings out a 'new version'.

The manufacturers can't release a 'full beanz' version of a new engine from the off otherwise they'd have to develope a whole new engine for future face-life models.

Hey, even the GTR has room for improvement...