VP vs. PD: Fuel Consumption Experiences

Hello everyone,

According to the diagnostic tool, my car has a respectable 135 horsepower at 1,500 kilometers, but compared to my old Golf 3, it still drinks a lot of fuel. With the same, economical driving style, the ASZ engine consumes about 5.3 liters, while the AFN engine was satisfied with about one liter less.

Okay, the Polo weighs about 60 kg more than the Golf, but its overall gear ratios (rpm to km/h) are approximately 10% longer in each gear. And the Polo's 6th gear is something the Golf can only dream of (180 km/h at 3000 rpm).
In addition, the Polo features electrohydraulic power steering, which is said to save approximately 0.2 liters per 100 kilometers in real-world driving conditions.

If you deduct the 0.2 liters that the Polo consumes due to its factory-fitted "Fuel Saver" tires, which have a very high rolling resistance, compared to the "only" heavily rolling 195 tires of the Golf, the Polo still consumes approximately 0.8 liters more.

I wonder where all that supposedly excellent fuel efficiency of direct injection engines goes, thanks to the finest atomization .

I have already checked and corrected the camshaft and PD element settings, and the crankshaft's timing sensor wheel appears to be correctly mounted. Initial data logs show no indications of issues with air mass or boost pressure.

At the start of the process, negative numbers are constantly logged, but the values appear plausible (idle -4°, up to -20° at full load).
With a two-stroke engine, those would be fuel-consuming and sooty misfires after top dead center, but if there's something fundamentally wrong with my engine, it probably wouldn't be able to deliver its full rated power.

The preliminary compression test on the downhill section is also normal, and the current oil consumption, for a new engine, is quite moderate at around 0.1 liters per 1000 km, in my opinion.

Overall, I'm increasingly suspecting that, despite having the same official fuel consumption figures as the Golf (5.0 liters in total for both), the Polo will always consume a bit more fuel in real-world driving.

What are the experiences of other people who have switched from a gasoline engine to a plug-in hybrid (PHEV), particularly regarding fuel consumption? (Ideally, the experiences should be from people who made the switch with vehicles having roughly comparable engine power, vehicle weight, and driving profiles in both the old and new cars.)

While I'm carrying a significantly heavier load (around 200 kg more) in my Passat, I drive a route where I don't often need to brake or accelerate. The new Passat consumes about 0.6 to 0.9 liters more per 100 km (35i: 5.2 - 5.5 liters, 3B: 6.1 liters). The 35i had 90 horsepower, while the PD now has 115 horsepower. However, it shouldn't make a noticeable difference in normal driving conditions, as you generally have almost the same turbo boost and power output when driving continuously.

Here's the translation:

'I've read that Passat 3BG drivers with the 130 hp PD engine sometimes achieve slightly lower fuel consumption if they rev the engine a bit higher (instead of shifting at 2,000 rpm, they shift up at around 2,500 rpm).'

Best regards, WarLord.

Hello!

I've had similar experiences.

I have the AFN (110 hp) engine in my Golf 3, and I've often found that its fuel consumption is comparable to that of the...
Comparing a Golf 4 with a 100 horsepower PumpeDüse engine (as a rental car). The latter always consumes approximately 1 liter.
swallowed more, although with wider tires, but also at a very moderate speed.

I have measured the average fuel consumption (AFN) many times while driving at a constant speed of approximately 60-70 km/h, and I always saw values between 3.2 and 3.6 on the MFA (Multi-Function Display), which averages out to about 3.5.
I have always observed significantly higher values (on the instantaneous display) with the PD.
I don't know what it looks like when driving faster.

What is the stated fuel consumption for out-of-town driving in the owner's manual?
For the G3 AFN, it's 4.1.

Greetings, Klaus.

Hi,

Okay, but don't forget about the driving forces that the motor itself consumes!

For a long time, this was the problem with CR (Common Rail) engines compared to VP (Variable Pump) engines. Because the CR pump requires more force, the engine simply consumes more power and therefore uses more fuel. Unfortunately, PD (Positive Displacement) elements also have this characteristic.

By the way, the long-term average fuel consumption difference between my G3 and my G4 PD is exactly -0.2 liters. I actually consume less fuel with the PD than with the VP!
However, I can already say that for WoWa trips, the required performance demands significantly more fuel than with a VP (presumably referring to a different type of vehicle or system).

Hi Ulf!

'1500km is nothing for an engine like that. Even after 100,000km, you usually won't see any wear on the piston rings/liners/bearings, etc., under normal circumstances.'

During my time at Mercedes-Benz, we once disassembled a 220CDi with 148,000 km, and there was absolutely no measurable wear. Not even the valve stem seals were hardened, although that plays a minor role in a diesel engine.
Unfortunately, the engine failed because a badger gnawed on the lower radiator hose, which then burst due to the pressure; since this was a company car, this happened at speeds exceeding 200 km/h. *Smoke*

My AWX engine consumes approximately 1 liter less fuel compared to the ALH engine, despite carrying about 200 kg more weight and producing 40 horsepower more.
'In terms of long-term fuel consumption, I'm getting around 5.7 liters with the PD engine, while the ALH engine consumed about 6.7 liters with the same driving style. My driving is gentle only when the engine is cold; otherwise, I tend to drive quite fast (over 180 km/h).'

Gremlin already told you that a noticeable increase in engine power comes after 10,000 km. While I personally don't believe in a software-based 'break-in' program, there's a lot of evidence to suggest it. I only managed to climb my comparison hill here in Wü (3rd gear, no acceleration, right-hand turn uphill, about 250 meters long, quite steep) with the AWX after approximately 10,000 km.
Before, it would always stall in third gear, both when cold and when warm (the RPMs are only 1200 there), and I had to shift back down.
Now, I can even drive up that hill in third gear with a fully loaded car.

Because your car is not lowered, the air resistance also increases.

Klausel wrote:

What is the stated fuel consumption for out-of-town driving in the owner's manual? For the G3 AFN, it is 4.1

.
Hi Klaus,

The ASZ Polo also lists a fuel consumption of 4.1 liters per 100 km (city = 6.6, combined = 5.0).

Bertil wrote:

So, one thing you absolutely must remember, but very strongly, is the driving forces that the motor itself consumes! For a long time, this was the problem with CR (Common Rail) engines compared to VP (Variable Pump) engines. Due to the higher power required for the CR pump, the engine simply consumed more power and therefore consumed more fuel. Unfortunately, PD (Positive Displacement) elements also have these same characteristics.

Hi Bertil,

Based on my intuition, I agree with your argument: finer atomization inevitably requires more energy.
Then I wonder how they managed to achieve the same fuel consumption figures for the ASZ Polo as the AFN Golf .

It seems that Julian and you using PD engines consuming less fuel than VP engines is rather an exception (and shouldn't actually happen due to the higher power requirements of the PD engines). What were your long-term average fuel consumption figures for both cars?

It seems that Julian and you using PD engines consuming less fuel than VP engines is rather an exception (and shouldn't actually happen because PDEs have a higher power demand). What were/are your long-term average fuel consumptions with both cars?

Hmm, didn't someone post here before that the maximum injection volume is lower for PD injectors than for VPE injectors?
Seeing the sophisticated generator control or climate compressor control systems alone, it's no surprise that the energy consumption is low.

In a PD (presumably referring to a diesel engine), the explanation is straightforward: it has a longer stroke and a lower engine speed. This means fewer revolutions per unit of time, which results in less fuel injection per unit of time.

'With the ALH engine, I was able to reach just under 140 km/h in 5th gear at 3000 RPM, but with the AWX engine, it's closer to 165 km/h.'

'My fuel consumption test at a constant speed of 100 km/h also speaks in favor of the AWX engine: the ALH engine always consumed around 4.0 liters, while the AWX consumed around 3.3 liters.'

The long-term fuel consumption is indicated at the top; for the ALH engine, it's approximately after 160,000 km, and for the AWX engine, it's now after over 25,000 km.

You can really feel the extra 200kg in city driving; the AWX engine needs a bit more fuel, and consumption quickly rises to 7-8 liters. The ALH engine was more economical. But there's definitely a difference between constantly accelerating a car that weighs 1370kg versus one that weighs 1580kg.

ulf wrote:

Bertil wrote: So, one thing you absolutely must remember, but pay very close attention to, is the driving forces that the motor itself consumes! For a long time, this was the problem with CR (Common Rail) engines compared to VP (Variable Pump) engines. Due to the higher power required for the CR pump, the engine simply consumed more power and therefore consumed more fuel. Unfortunately, PD (Positive Displacement) elements also have these same characteristics. Hi Bertil, Based on my intuition, I agree with your argument: finer atomization inevitably requires more energy. Then I wonder how they managed to achieve the same fuel consumption figures for the ASZ Polo as the AFN Golf .

Possible!

Quote:

It seems that Julian and you using PD engines consuming less fuel than VP engines is rather an exception (and, given the higher power requirements of PD engines, it probably shouldn't happen at all ).

Not necessarily, I know of other PD "Artisten" models that initially consumed significantly more, but later ended up using quite a bit less.
The engines seem to require an extremely long "normalization" period. In some cases, the fuel consumption (oil - fuel) doesn't stabilize until after 10,000 to 15,000 kilometers.
In my opinion, the PD motor requires a slightly different driving style (to achieve lower fuel consumption), which takes quite a while to get used to. It took me about 8-10 tankfuls to adjust.

Quote:

. . . where were / are your long-term average fuel consumption figures for both cars?

6.0-6.1 liters for the 1Z engine.
5.7-5.8 liters for the AXR engine.

For all values, WoWa trips have been excluded.



Sure, here is the translation of the text from German to English:

"Addendum:"
"I achieved the lowest fuel consumption last weekend during a trip of 315 km, with an average speed of 78 km/h, consuming 4.8 liters per 100 km. This included approximately 170 km of country roads and the rest was highway driving with the cruise control set to 100 km/h. Unfortunately, the country roads significantly increased the fuel consumption."

Hi Ulf,

I can only compare my G3 Variant 1Z with my colleague's Bora Variant 100PS.

The gearboxes should be almost identical (both around 140 horsepower at 3000 RPM).

When I ride my scooter (going uphill, it uses 150 watts, and on a flat surface 180 watts, that's the maximum), I consume a maximum of 6.2 liters of fuel per 100 kilometers - normally it's 5.5 liters.

When he drives his Bora to Bavaria, even at speeds of around 180 km/h with the GRA (presumably a performance upgrade), the MFA (Multi Function Display) indicates fuel consumption of around 8 liters.

Okay, the Bora probably weighs a bit more than my G3 (around 1400 kg) due to the Climatronic system and other features, but the difference is significant, especially at higher speeds.

However, you can definitely feel the extra 38 Nm of torque and 10 horsepower when we're out riding together.

m;

PS: Last summer, we drove my sister's Renault Megane station wagon (1.9 dci, 102 hp) with 3 adults, one child, a roof box, and air conditioning to the Atlantic coast, and it managed to get us there with an average fuel consumption of 4.8 liters per 100 km! Otherwise, it's a terrible car!!!

Hi Ulf.


When I ride my scooter (going uphill, it uses 150 watts, and on a flat surface 180 watts, that's the maximum), I consume a maximum of 6.2 liters of fuel per 100 kilometers - normally it's 5.5 liters.



I simply asserted that it couldn't be possible!
Full throttle and only 6.2 liters per 100 kilometers? That's impossible!
I have the same engine, and it uses more fuel at full throttle! But definitely, it's a factor.

Best regards,

Hi,

"I agree with 'Wurstblinker'. When I drive with the 'aggressive' driving mode on the highway, I also get over 7 liters per 100 kilometers. It's understandable, because at speeds of 180 km/h or more, the instantaneous fuel consumption is well over 8-10 liters, and it's difficult to bring that down to 6."

The other day, I was driving at 7.3 kilometers per minute, which is equivalent to Berlin to almost Cologne. For the first 250 kilometers, I rarely drove below 190 km/h on the A2 (as long as it was open and traffic allowed). Afterwards, it was slower, but I occasionally reached 200 km/h, although there were also longer stretches at a constant 130 km/h.

7.3 is fine, but a gasoline engine would probably consume over 10 liters.

Best regards,

Jan.

Wü -> Muc: 300km, Average speed 148km/h, Fuel consumption 6.3 liters/100km

Jan6K wrote:

7.3 is fine, but a gasoline engine would probably consume over 10 liters.

Golf4, 100 horsepower, common rail (PD) engine, mileage approximately 600 km, average fuel consumption according to the onboard computer (FIS) is 7.8 liters.
The car was only driven at its maximum speed on the designated track, and the engine was always revved up to approximately 4000 RPM.
"I use the same car for my commute, which is about 60km, mostly on country roads, and I get around 6.5 liters per 100km with normal driving. I'm just trying to get a reasonable fuel consumption out of the car, driving as I normally do. On the same route, my Golf 3 with a 1Z 90hp engine gets about 5.3 liters per 100km, but I tend to drive it a bit more aggressively than the Golf 4."

Another bill from last time:

Würzburg to Munich, average speed 166 km/h, fuel consumption 7.1 liters per 100 km.

Of course, I don't drive the entire tank of gas with a lead foot.

I mostly ride around in the city, and then there are usually 2-3 instances of what I call "heating orgies."

But, as far as I know, my friend also drives that model.

If I drive a bit more moderately, I always get close to 1200 on the daily kilometer counter )))

(My fuel tank has an aneurysm , and it easily consumes 68 liters.)

dieselmartin wrote:

Hi Ulf. I can only compare my G3 Variant 1Z with my colleague's Bora Variant 100PS. The gearboxes should be almost identical (both around 140 horsepower at 3000 RPM).

That is almost impossible!
My 1Z estate car was specified with a top speed of under 180 km/h, while the AXR engine is specified with a top speed of 188 km/h. Interestingly, the rev limiter on the AXR is even lower than on the 1Z.
When I'm following trucks with my AXR (with a WoWa attached), I'm in 5th gear and my engine speed is about 200 RPM lower than the engine speed of the trucks. I doubt that the trucks' engine speeds suddenly slowed down compared to my AXR.


It is well known that PD engines tend to "consume" more fuel during aggressive driving, but this is a characteristic of almost every modern diesel engine, including common rail (CR) engines. Today's diesel engines are just as sensitive to the accelerator pedal as their gasoline counterparts. Nevertheless, the fuel consumption level is still lower.

I still remember my first G1 D (1.5L, 37 kW/50 hp) very well. No matter how heavy your right foot was, it was possible to influence the fuel consumption. With the 70 hp TD, it started to become more noticeable, and over the years, diesel engines became increasingly powerful and fuel-hungry when full power was demanded.
For me, this is nothing unusual... you get nothing for nothing!