My 2003 Renault Clio 1.5 dCi - 3.7L/100KM TANK!

[HowGudAmI]

Hi Everyone - I am a long time lurker on here - in fact, over three years ago, I posted a thread up about improving the economy (I was getting about 30 imperial MPG) I got out of my 1983 Austin Mini!

Because I ran that car on a shoestring, I couldn't really give it the attention it needed, to get the economy it should have (there was something wrong with the ignition advance, I believe).

Since then, I have been mostly car-less - I did spend some time driving my other half's 1.3 petrol Ford KA which between us we got about 44 imperial MPG out of. And more recently, I spent a lot of time driving rental cars for work, most of which were 1.6 diesels that saw over 60 imperial MPGs (90% motorway doing 70-75mph).

Anyway, me and my OH (who will be sharing the car, and won't drive quite as economically as me) bought a car just over a week ago - and it's a bit different to the usual that you will see on here, because we're from the UK (as you probably guessed by the classic Mini, and imperial MPG's).

It's a 2003 Renault Clio with a 1.5 turbo diesel engine producing 80hp, it weighs about 1000 kilos and the official EU economy figures are:
Urban: 53.3 MPG (44.4 US, 5.3L/100km)
Extra Urban: 76.3 MPG (63.6 US, 3.7L/100km)
Combined: 67.3 MPG (56.0 US, 4.2L/100km)

That sounds like a lot - but for those that don't know - the EU economy tests are a lot 'easier' than the US ratings. If the car got an EPA figure, it would probably be about 45 US mpg highway / 36 US mpg city.

I haven't ran a full tank through it yet (the car has a 50L capacity), and the economy readings from Torque Pro on my phone don't seem to be accurate... so who knows what I will get. It will probably be on the low side with room for improvement .

It would be nice to see 71 MPG (59 US, 4L/100km) with a little effort which would put me well in the top 10 on here for diesel. Usage will be mixed, stop start city driving, a 40 mile each way motorway journey a couple of times a week, and some fun weekend trips.

Here are a couple of pics from the day we picked her up:



It's not fast or sexy but it will hopefully make up for that in its running costs.

[HowGudAmI]

Well, I guess I should go a little more into my goals and intentions.

Firstly, I want to keep the car a nice place to be, by that, I mean I will be keeping the standard sound deadening, stereo, rear seats, and using the AC when its hot (though luckily that isn't too often in the UK). I will also be keeping the spare wheel because I don't want to be left stranded with a puncture.

Secondly, I am not sure yet how much in the way of mods I will explore. When we got it, the front wipers needed replacing, so I swapped them for Bosch Aerotwin ones which are a more modern, low profile design (they old wipers are visible in the above photos) - they probably do a tiny bit for reducing drag - but I mainly got them because they are better than stock wipers.

I also fitted some Team Heko wind deflectors, which probably increase drag slightly when the windows are closed - but I wanted some anyway (they reduce turbulence with the windows down, and keep rain off the door card too).

I am not sure what to do with the wheel trims yet, I am thinking about removing them... the question is, are they more aerodynamic than the bare steel wheel?...

The stock ride height is quite high (though body roll and road holding are pretty good), but I doubt lowering the car would pay for itself in fuel savings. Perhaps an air dam would be more effective...

I have also been thinking about a grill block... but am concerned about how this would affect the front mount intercooler and air intake temperatures.

I am currently running tire pressures just a touch over the recommended levels (35psi on the front, 32psi on the rear vs 32/30 recommended). When the tires need replacing, I will be going for a low rolling resistance option, but the current tires have a lot of life left in them.

Lots of things to think about... what do you all think?

[oldtamiyaphile]

Originally Posted by HowGudAmI

I am not sure what to do with the wheel trims yet, I am thinking about removing them... the question is, are they more aerodynamic than the bare steel wheel?...

Probably.

I have also been thinking about a grill block... but am concerned about how this would affect the front mount intercooler and air intake temperatures.

Leave the area in front of the IC open, and block the rest, you can also leave the intake side open or make a deflector into the intake. That's how I did it on my TDI.

[HowGudAmI]

Originally Posted by oldtamiyaphile

Leave the area in front of the IC open, and block the rest, you can also leave the intake side open or make a deflector into the intake. That's how I did it on my TDI.

Not my engine bay, but the same model - http://i24.photobucket.com/albums/c4...2022010243.jpg

In stock form, the air intake runs to the side of the engine bay and opens out by one of the headlights.

I can block the upper grille without affecting the IC, and I would keep an eye on how this affects intake temps... which might not actually be too bad given it doesn't directly use the front grille.

Alternatively, I could reroute the air intake to the front grill, and do a partial block.

Which would be the better option here?

Thanks .

[HowGudAmI]

Bit of an update here, I refilled my car after 347 miles (though it did have just over 1/3rd of a tank left) - it took 28.31 litres.

That works out at 55.73 UK MPG (46.4 US, 5.07L/100km) - which is about 17% below the car's official UK combined figure - and about equal with what I would expect its US highway rating to be (if it had one).

I am relatively pleased with that as a starting point. The mileage was split up with about 1/3rd motorway (cruising at about 75 indicated), 1/3rd country driving (average speed of about 50, lots of hills etc - had a bit of fun in parts - which was obviously detrimental to FE) and 1/3rd stop start city traffic (5 miles to work - average speed of about 10mph).

Since I last posted, I have changed the diesel filter (where I lost a small amount of fuel) and the cabin and air filters. The wheel trims have also come off - because one of them had split - on the lookout for an aerodynamic replacement (or possibly lighter alloys, if funds allow).

I am hoping to improve on this figure over the next tank. I have already put 210 miles on it (two trips of 104 miles (plus 2 town miles) with an average speed of about 50 for both - 70% motorway at around 75 and 30% country at various speeds - but not much traffic on either). I intend to drop my motorway cruising speed by about 10%, and may also raise my tyre pressures (but they were still the same for the last 210 miles). I am changing my oil and filter soon - using a quality fully synthetic 5w40 (current oil is unknown).

I looked at a grille block, but the intercooler pretty much covers the entire area that is open... so am probably going to leave it.

I have been keeping an eye on temps, my engine tends to run at around 85C and warms up reasonably quickly. my intake temperature runs at around 8C above ambient, which at this time of year means about 15-20C - I am not sure what is best for FE here?

It would be nice to see a 10% improvement this tank, and I still have my sights on the top 10 diesels (perhaps before the year is out?), which means I need to get about 54 US MPG (65 UK, 4.3L/100km).

Also, most of my driving so far has included two people in the car, and also the odd boot full of stuff too!. Going forward, there will be more miles with just 1 occupant and little 'cargo'. I am not sure how much difference this makes but it must be something?

New pics just because:

[Piwoslaw]

My Dad-in-law has a Nissan Note with a 1.5 dCi, but the closest he's ever come to ecodriving was when he was my passenger. But I'm sure it's hardly different from my 1.6 HDi, so the same engine mods should work.

Grille block. If you are debating how much to cover, then make it openable. Behind the grille the airflow is channeled to the radiator and to the intercooler - each can be independently closed off. As you won't have too many cold starts when it's -20C, then no need for you to block the IC at all.

Prewarming the engine with a 550W coolant heater and a 125W heating pad under the oil pan does wonders if you can organize a place to plug in. I've added insulation to the bonnet, oilpan and intake ducts (turbodiesel engines should be hot, but with cold air intake, both for power and economy). This makes the prewarming more effective, but also keeps the engine from cooling too much when parked for 1-3 hours while running errands.

An engine kill button will let you EOC without reseting the onboard computer. In my case, it keeps the power steering active and (more importantly for Mrs P) does not reset the radio/CD player

The Clio's rear is not Kammback-friendly, but bumping the tyre pressure (try max sidewall minus 10% for starters) equals free MPGs

It is driving technique that gives the most savings (15-30%), but works even better when paired with mods. For example grille blocks keep your engine warm, but efficient driving keeps the blocked engine from overheating.

I'm lucky to have a wife who also drives the speed limit and cares about saving fuel* And even though she does not engine brake as often, nor does she EOC at all, she can still get figures very close to mine

*) Does not apply to all Significant Others

[HowGudAmI]

Thanks for the detailed response Piwoslaw

Originally Posted by Piwoslaw

Grille block. If you are debating how much to cover, then make it openable. Behind the grille the airflow is channeled to the radiator and to the intercooler - each can be independently closed off. As you won't have too many cold starts when it's -20C, then no need for you to block the IC at all.

As far as I can tell (memory from a glance a few days ago), the IC covers all of the grill openings, the grill at the top is even partially 'closed' (there is solid plastic behind the 'mesh' angled towards the IC).

Originally Posted by Piwoslaw

Prewarming the engine with a 550W coolant heater and a 125W heating pad under the oil pan does wonders if you can organize a place to plug in. I've added insulation to the bonnet, oilpan and intake ducts (turbodiesel engines should be hot, but with cold air intake, both for power and economy). This makes the prewarming more effective, but also keeps the engine from cooling too much when parked for 1-3 hours while running errands.

I live in a flat, so I don't think I will be able to pre-warm. The bonnet already has some (presumably factory fitted) insulation... maybe some more should help. The air intake seems pretty effective already (air is 8-9 deg C above ambient). Perhaps I should look into an undertray with insulation...

Originally Posted by Piwoslaw

An engine kill button will let you EOC without reseting the onboard computer. In my case, it keeps the power steering active and (more importantly for Mrs P) does not reset the radio/CD player

I -think- my car has electric power steering rather than hydraulic. I will have to look at how much wiring is involved (and how much benefit there is vs. engine on coasting).

Originally Posted by Piwoslaw

The Clio's rear is not Kammback-friendly, but bumping the tyre pressure (try max sidewall minus 10% for starters) equals free MPGs

Kammback is beyond what I would want anyway (to be honest, I will probably be more focussed on technique than anything). I am still not sure about bumping the tyre pressures regarding grip/road holding and wear (keeping it even).

Originally Posted by Piwoslaw

I'm lucky to have a wife who also drives the speed limit and cares about saving fuel* And even though she does not engine brake as often, nor does she EOC at all, she can still get figures very close to mine

*) Does not apply to all Significant Others

My SO does not drive aggressively, but does not have the most eco mindset either.

A common week for us going forward will be me using the car 2 or 3 days, making two 35-40 mile trips (90% motorway) separated by a few hours, and her using the car on the other 2 or 3 working days, making two 5 mile stop-start trips separated by a full day.

[oldtamiyaphile]

Originally Posted by HowGudAmI

I -think- my car has electric power steering rather than hydraulic. I will have to look at how much wiring is involved (and how much benefit there is vs. engine on coasting).

My Kangoo has EPAS, everything continues to work while EOC (the odo does loose miles though so I use GPS for that). The kill switch is really just for LHD vehicles where the ignition switch is on the right, so they have to kill the ignition and shift with the same hand. If the Clio is anything like the Kangoo, the wiring is extremely difficult to get at.

With a turbo diesel, EOC is probably not worth the savings vs potential risk of turbo damage. I used to EOC the T5 sometimes but only if the turbo had already been given a good chance to spool down.

[TimV]

The European fuel numbers are hard to beat. But it is possible.

Take a look at my car.

Best tank of this summer is 5,2l/100km.
1302km on the odo with around 72l to fill up.

[Piwoslaw]

Originally Posted by oldtamiyaphile

With a turbo diesel, EOC is probably not worth the savings vs potential risk of turbo damage. I used to EOC the T5 sometimes but only if the turbo had already been given a good chance to spool down.

Exactly. That's why I only kill the engine when rolling to a red light, or when I know that I'll get close to 1 km of EOC (my record is 6km in the Alps). Shorter distances are just not worth it.