VW Mk4 Golf Estate 1.9SDI

[1.9SDI]

Hello all, I own a VW Golf Estate in the UK (would that be Rabbit Stationwagon or Golf Variant overseas?). As the first wave of Fuel Duty increases has taken effect today, VAT increase on the 4th Jan and a further Fuel Duty increase later in the year, I thought it would be time to see what I could do to save fuel money by making it go further.

I drive about 10k miles per year and already follow many of the fuel saving driving techniques. Documented fuel consumption is 44MPG on a mixed cycle but I can easily achieve 53MPG and can approach 67MPG on highways at 65MPH average. I never exceed 2000RPM except in 5th gear.

I've already ordered a suspension lowering kit (aluminium body coilovers) which not only increase aerodynamic efficiency but also save weight on the steel originals. I've been trying to find lightweight lower control arms (pressed steel) and hubs (cast iron?) but no luck so far, plus there's a huge potential saving in the rear suspension system. Continuing the weight saving theme, I've dumped the spare wheel and bought a couple cans of tyre weld and a 12V air compressor. I've also bought some cheap used alloy wheels from an Audi A3 and increased pressures to 45PSI.

Planned mods after fitting the suspension upgrade is to convert to 100% biodiesel, saving me at least 25% on fuel costs. Also to continue with a few aero mods and any more weight saving mods I can easily and cheaply do. One of those will be replacing the wing mirrors with smaller DTM Cup mirrors which are about half the area of the originals. And, by careful scanning of ebay, I'd like to find some even lighter alloy wheels and cover with smooth discs, and maybe reduce the width of the tyres from 195mm to 165mm. I'd really like to know how to ease the airflow over the wipers, if anyone knows?

Also, does anyone know if it's worth swapping the hydraulic power steering to electric? The pump robs nearly 8HP under load (and a coresponding amount of fuel) and even when not in use still uses power to pressurise the system. Obviously this will put more load on the alternator but is the trade-off worthwhile? Also, on an alternator related theme, I could change the rear lights for LED versions and the headlights to 35/35HID bulbs. How much of a saving on the alternator load (and fuel) would this be?

I have a few engine mods planned - most dramatically the bio conversion. But I also want to find out if the ECU can be mapped for economy, and find out if there are more efficient fuel delivery systems available (injection system)? This is my first diesel so I'm also keen to find out if there are more efficient inlet and outlet manifolds, if anyone knows?

So, to recap, I've broken down my mod categories as follows, in priority:
1. Engine efficiency
Biodiesel conversion
ECU remapping?
Fuel delivery/manifolds?
2. Aerodynamic efficiency
Lower suspension
Smooth wheel covers
Smaller mirrors
Wiper, vent, etc mods?
3. Weight savings
Remove spare wheel
Lighter, narrower road wheels
Replace heavy components?
4. Systems refinement
Electric power steering?
High efficiency lighting?
(the question marks are those mods that I'm not sure if they are worthwhile)
Are there any other mods that are proven to be cost effective?

I'm now off to read the forum stickys so I may well end up answering my questions, but feel free to chip in and add to my list.

Cheers, Steve.

[Ryland]

What year is the car?
It seems like alot of cars have power steering and didn't really need it, so you might check around and see if there is a non power steering rack standard on other versions of the Rabbit that would bolt right on.
Also be aware that some alloy rims are heavier then steel rims, finding out the rim weight is always a good idea instead of just assuming that alloy rims are light.

[1.9SDI]

Hello Ryland

It's a 2000 non-turbo diesel.

I'd probably need some form of power steering as the engine is in the front and it weighs as much as an elephant. I was just asking which is more efficient: hydraulic or electric power steering. I found a post here that says electric is more efficient as the hydraulic system is always being run whereas the electric system is only 'on' when you turn the steering wheel. That's good to know, I just have to work out the cost/benefit ratio and find somewhere that sells the conversion if it works out favourable.

Yes, I will see what size wheel I can get away with (larger the better) after the suspension upgrade. Currently 15" wheels with 65 tyres (stock) but I may go to 16" thinner wheels and lower profile tyres. I've found WheelWeights dot net as a good source of weights for a large range of wheels. I need to find the same for tyres.

Cheers, Steve

[1.9SDI]

A quick update and a story.

In addition to the suspension upgrade, I have now purchased a ScanGuage2 monitor and a pair of DTM Cup mirrors. Before I fit anything (other than the ScanGuage) I will do a few runs of mixed driving, mostly 100 mile day and night trips to get a fair result, and measure the MPG. I'll post all results here. I'll then complete all aero mods and note any changes.

An interesting story for weight savers. A friend of mine is restoring a classic car. He's stripping it completely and part of the process was pressure washing the underside. As an experiment he decided to weigh how much dirt and crud that came out - 12.5Kg! That's nearly 30Lbs of free weightsaving just by removing the dirt. Moral of the story: wash your car regularly to save weight.

Cheers, Steve

[robchalmers]

Hi Steve,

Good to have another brit on boarxd especially someone with a non-whirly 1.9 (granted yours s a bt more advanced than mine!)

the Power steerng is six/two-threes really and if your doing a lot of motorway its are that the it'll even kick in.

loving the the DTM mirrors idea, I'd try a grille block too as its one of the qickest ways to improve the aero and it can be done subtly , I'm guessing you're going for looks too!

Which 16" A3 alloys are you running? got to admit I'm intriged!

Start your fuel log soon - there is a a lot of potential in that there ride!

[1.9SDI]

Hello Rob, compadre!

About the power steering, my thinking is that the pump is continually being turned, therefore taking HPs away/adding to fuel consumption. The good thing about electric power steering is that the alternator is turning anyway - to charge the battery, etc so it doesn't matter if I load it a little more with a power steering motor. But my logic could be flawed?

At the mo I have 15" Audi alloys (take a look on fleabay at item no. 390276194556) but I'm thinking of getting bigger wheels if lowering doesn't fill the arches.

I'm trying to look for an aftermarket grill/bumper/spoiler combo that is mostly filled for neatness. I'd like to do it myself but I know I'd end up with pipe wrapped around my pulleys! I need to take the roof rails off and somehow make the wiper area more aero - there's a huge gap between the bonnet and the screen that just sings out 'turbulence'... With the addition of smooth wheels, all my aero mods would be done. I'd love to shave the door handles and grind off the gutters and seal the seams but that is a few steps too far for me.

I'm looking forward to getting the ScanGuage prior to making any mods so I can have a measurable and standard baseline to compare against. I'll do about 400 miles to provide my baseline. I may also start using biodiesel at the same time too.

Let me know of any tips you've picked up and what you think of the fuel price rises and what you're doing to combat them.

Cheers, Steve

[robchalmers]

Personally i think its time to get militant again. increases in tax, VAT etc the country won't be able to afford their own bills let alone the countries!

lower tax - which will increase sales, increases demand = more jobs

15% of something is better than
20% of F*** all

[1.9SDI]

I just thought, for any project you need to set yourself some goals and boundarys, so here are mine:

Goals
To keep her a reliable and practical family car
Increase economy to 60mpg (UK) on an urban cycle
Increase economy to 80mpg (UK) on a highway cycle
To spend no more than £1000

[ChrstphrR]

The scanguage is going to be your key tool here.

From my toying around with my TDI, I've found that just having good instrumentation teaches you the best way to drive more efficiently, and that makes the single biggest difference (and probably the second cheapest).

Given it's winter all around the northern hemisphere, blocking your grill, aggressively, will help with warmup times. My own setup on my 2000 TDI, consists of a 2/3 block with coroplast, left and right thirds of the radiator behind the grill openings (painted black so they're not visible from the outside).
I run with 1/3 or 2/3 block next to the radiator year round.

The bottom opening on the 4th gen VW Golf/Jetta tends to give the best airflow for cooling. If you don't need that due to the cold weather, you could readily block that up that opening itself.

If you want to be careful, block this opening progressively, and monitor temperatures. And aim for the ability to quickly remove out segments as needed. My first lower block was black plastic stretched taught over the black plastic insert in the lower opening. The time I did have higher temperatures and high humidity (98°C coolant, with 30°C air temperatures, at highway speeds), I simply opened up the plastic with a hole in the center using a pen knife. :P

Remember this is just information from a forum post, not a carefully controlled study, and you live in another region of the world, your mileage may vary with this tip, etc., etc.

[1.9SDI]

Thanks for the excellent advice Chris, and also for clearing something up. I thought blocking grills and vents was purely aerodynamic, not to get the engine to temp quicker. Thanks again!

Yes, the ScanGauge is what I need first. I used to drive a VW Tuareg 3.2 V6 petrol for a few years. During the last year or so I eventually found the fuel usage section on the computer and WOW, was I surprised. My lifetime average was 18mpg! From using the live display I was able to learn to drive economically and I carry that through today. I was footloose and fancy free then, now I have a child and financial responsibilies so every penny counts!

Thanks again for the advice, Steve