Remap for economy vs power.

My TDI 90 had a re-map before I bought it by AMD in Oxford. Aparently it produces 112bhp.

I have never been that happy with the fuel consumption. Even when I drive carefully I only get in the high 58ish.

I'm wondering if I could trade off some of that power for some improved mpg and also wondering if I can have my cake and eat it by having both power and economy.

Cheers
 

A2Steve

A2OC Donor
Remaps usually improve the mpg of a car not the other way around. Mine is remapped and not driven with economy in mind and gives back 60 odd mpg normally. How well serviced is your car? A dirty air filter on a TDI can have a far more detrimental affect than you would think.
 

Special edition

Admin Team
Hi Alfie,

My remapped 90 by stealth took the power up to 116bhp. I never really used it that much apart from motorway sliproads but when driven at low speeds and revs it actually improved the MPG. I would think that 58mpg is quite good but it would depend on your driving style, outside temperature and length of journey.

Cheers
Dave :)
 

Rince

Member
I had my TDI 75 remapped to about 108-110 and if I stick my foot down, I get about 45 - if I drive it carefully, into the high 60's and low 70's.

Driving style and speed make a huge difference.
 
I also find that un-sprung wieght is a substantial factor in mpg too.

During the winter months I usually fit the 15" polished A2 rims, which are almost as light as the pepper pots.
During the summer months I run a heavy 17" Ronal, which is very, very heavy.

I notice at least a 10% increase in fuel usage when using the heavy wheels - and if I'm wanting to "press on" then that can rise to 15%-18%.

In real terms I can get upto 10mpg better consumtion over a 50 mile each way, 3 times a week commute, from a cold engine on each leg, so 6 x 50 mile cold starts = 60mpg summer wheel or 70mpg winter wheels.

Cheers
Jeff
 

Birchall

Dick Chown Award 2016
A remap gets the extra power mainly from burninjg the fuel more efficiently and so yes, it normally improves MPG.

BUT and it is a big BUT. The fact that you have more power means that you are more likely to use it and that harms the MPG.

So if you get a remap and drive the same as you always did then you will get better MPG !!!

If you use the right remap company they can tailor the map more towards MPG than MPH too.

Steve B
 

depronman

A2OC Donor
I concur with the above statements -
A good remap normally slightly improves the MPG, providing that your driving stile pre and post remap remains the same. if you use the extra power/rev range then the MPG will suffer.

Driving style/speed/outside temperatur/number of cold starts is certainly the biggest factor which affects MPG. I have noticed that in these cold winter months and my 8 mile to work commute my MPG as dropped from mid 60mpg to mid 50mpg. On a couple of 100 mile motorway trips I was back up to low 60, so ambient temperature certainly as an adverse affect on diesel engines (maybe more so than it does on Petrol engines)

Cheers,
 

depronman

A2OC Donor
I also find that un-sprung wieght is a substantial factor in mpg too.

During the winter months I usually fit the 15" polished A2 rims, which are almost as light as the pepper pots.
During the summer months I run a heavy 17" Ronal, which is very, very heavy.

I notice at least a 10% increase in fuel usage when using the heavy wheels - and if I'm wanting to "press on" then that can rise to 15%-18%.

In real terms I can get upto 10mpg better consumtion over a 50 mile each way, 3 times a week commute, from a cold engine on each leg, so 6 x 50 mile cold starts = 60mpg summer wheel or 70mpg winter wheels.

Cheers
Jeff
Jeff,
Interesting comment re un sprung weight affecting MPG, are you running the same width tyres on both the 15 and 17 inch rims ? are they the same profile ?
I am trying to understand if it is the weight of the rims or the tyre contact area on the road.
My wife as a Pug 107 and when we bought it it had a set of after market TWR alloys with wide low profile tyres, it stuck to the road and you could throw it into bends and it just stuck to the road :)
However she complained about the steering being heavy and so when it came time to replace the tyres I bought a set of near new steel wheels (originals) with near new std size tyres. Now the Std tyres are some what higher profile and quite a bit narrower, but the rolling diameter of both new and old where identical.
We noted a noticeable in increase in the miles per tank, about an extra 60 miles per tank to be exact, the steering is much lighter as well so happy wiffy, but it does not corner as well :(

So in summary the narrow tyres reduce the rolling resistance and hence the better economy.
I don't think there was any great difference in the weight of the steel wheels/tyres compared to the alloys/tyres

Cheers,
 
Hi Paul,

No, the two sets of wheels have totally different tyres, so rolling resistance will certainly play a part in economy, or the lack of it.

I cannot remember what tyre size I'm running on the 15's but usually Goodyear brand, but my 17's usually are shod with Conti sport contact 3's at 215x40.

The different sets of wheels have substantially different weights in my case.

So I'm sure it's a mix of both rolling resistance and rims, but the point I was trying to make was that if you want to sacrifice asthetics (and more than likely grip and performance too) for MPG, changing all year round to lightweight rims (with better rolling resistance properties of the tyres :eek: ) will give you a good MPG gain.

The next question from the above statement though is, why choose to run a remapped TDi90 with little skinny rims when a TDi75 is likely to be the more frugal choice of ride anyway..............

So many choices............I know the way I'd go.......

Keep the 90 with a nice set of lovely rims and don't worry about shaving a few MPG - enjoy the car, both in looks and performance.

Cheers
Jeff
 

depronman

A2OC Donor
Hi Paul,

No, the two sets of wheels have totally different tyres, so rolling resistance will certainly play a part in economy, or the lack of it.

I cannot remember what tyre size I'm running on the 15's but usually Goodyear brand, but my 17's usually are shod with Conti sport contact 3's at 215x40.

The different sets of wheels have substantially different weights in my case.

So I'm sure it's a mix of both rolling resistance and rims, but the point I was trying to make was that if you want to sacrifice asthetics (and more than likely grip and performance too) for MPG, changing all year round to lightweight rims (with better rolling resistance properties of the tyres :eek: ) will give you a good MPG gain.

The next question from the above statement though is, why choose to run a remapped TDi90 with little skinny rims when a TDi75 is likely to be the more frugal choice of ride anyway..............

So many choices............I know the way I'd go.......

Keep the 90 with a nice set of lovely rims and don't worry about shaving a few MPG - enjoy the car, both in looks and performance.

Cheers
Jeff
I could not agree more, unless you are doing a stella millage the savings made on fuel between 55 and 60 mpg are negligible over a year
 

unipower

Member
A couple of observations on the effect of different wheels and tyres...
I had the standard 5.5 x 15in 7 spoke lightweight wheels on my first 1.6 Fsi.
Did about 115 000 miles over two sets of 175/60 Michelins.
Then changed to 165/65 Kumhos (Michelins no longer available). I wanted to see the effect the very slightly taller tyre wall (comfort/slight gearing change) and narrower profile (aerodynamic drag). Ran for another 15 000 miles before selling.
Car always felt nimble, with light steering, especially with the Kumhos. Not convinced the fuel economy changed much - 51-52mpg over the 130 000 miles seemed good to me. Tyre pressures were 2.2 - 2.3 bar.

With wider & bigger dia tyres, apart from the tyre rolling resistance I suspect the aerodynamic drag may be worse due to both the width of the tyre and the fact that the wheel arches get quite 'full' so air turbulence with the rotating wheel & tyre may affect economy too.

Current 1.6Fsi has the 6 x 16in wheels and 185/50 tyres, and the wheel/tyre mass does feel greater (steering & ride). Fuel consumption seems slightly worse than on the first car, but there are too many other variables to know whether the wheels and tyres make a difference.

Mark
 

timmus

A2OC Donor
I also find that un-sprung wieght is a substantial factor in mpg too.
Agreed. I normally run a set of 16" 7J alloys, but I also have a set of very light 15" alloys that I use on occasions. I think they're either 5.5J or 6J. Either way, when doing long-distance motorway trips, I notice only a tiny difference in fuel consumption, presumably due to the smaller contact patch. However, when doing lots of urban start-stop-start driving, the lighter wheels are noticeably more efficient. Physics says this ought to be the case as weight on wheels counts twice; you have to give the wheels both lateral momentum and rotational momentum, the energy for which comes from your fuel.

Cheers,

Tom
 
Hi Alfie,

My remapped 90 by stealth took the power up to 116bhp. I never really used it that much apart from motorway sliproads but when driven at low speeds and revs it actually improved the MPG. I would think that 58mpg is quite good but it would depend on your driving style, outside temperature and length of journey.

Cheers
Dave :)
58 mpg is the best I can get with a 50/50 mix of town and motorway with a max of 2500rpm and no heavy throttle. If I drive with light throttle and change up a 2000rpm I can get to 60mpg. A long motorway drive (about 200 miles) gave about 64mpg with a typical speed (cruise control) of 65mph.
 
I had my TDI 75 remapped to about 108-110 and if I stick my foot down, I get about 45 - if I drive it carefully, into the high 60's and low 70's.

Driving style and speed make a huge difference.
Have never seen an average of anything like 70mpg. As stated I drive very lightly. Brakes last years!
 

depronman

A2OC Donor
Alfie,
Assuming your fuel figures are from the current 'cold' ambient temperatures I think you are doing OK on the MPG front
 

ecoangel

Active Member
Pretty much all eco cars have smaller wheels and higher profil narrow tyres than sports versions. Compare Golf GTi with Bluemotion models. Several tests are online including one about a BMW 3 series.

Unsprung weight has a significant effect on MPG - and most of it is wheels rather than tyres. The 1.2 TDI and Lupo 3L have 14 inch 4 bolt mag wheels. The Audi version has 145/80R14 tyres.
 

Cloth Ears

A2OC Donor
58 mpg is the best I can get with a 50/50 mix of town and motorway with a max of 2500rpm and no heavy throttle. If I drive with light throttle and change up a 2000rpm I can get to 60mpg. A long motorway drive (about 200 miles) gave about 64mpg with a typical speed (cruise control) of 65mph.
Hi, I have a TDI90 Sport, and over my 12 years of ownership (110,000 miles, or thereabouts) my average mpg has tended to be around 50. On a run, that easily extends to around 55-60, unless I cruise at ahem mumble mph on the motorway, in which case low 50s. But my most regular driving, the daily commute, is a 50/50 mix of 70mph motorway and stop-start town traffic. The 13 mile commute can take up to an hour, which shows you how bad the stop-start traffic can be (sometimes, including most of the motorway). So, while I'd agree that driving style is important, the type of traffic conditions can make or break the overall mpg figures.

My driving style is pretty smooth - brakes last me ages - and I don't like to lug the engine. I believe the DMF is more prone to fail if your driving style is high torque at low revs, so I tend not to push it, until I have 2000rpm on the tacho.

Interestingly, I've used different fuels in my time, regular diesel averages around 49-50 mpg, BP Advanced/Shell Optimax around 52mpg, but the best figures (54 mpg average) have come since I started using Costco Premium diesel, a few months ago. Car seems to like it, and runs sweetly on it, too.

I'm in Manchester, and could be tempted by the depronman remap. I was toying with the idea of letting Awesome do a remap (they do my regular servicing), but TBH, wasn't looking forward to all that full-throttle running on the rolling road.
 
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