Geek Post: Modern Tech/Fuel Consumption

[Ares]

I'm well aware that the combination of diesel power and fuel consumption is enough to boil blood for many.....(so you can stop reading now).....but long journey over the weekend showed how much engine technology has developed.

I'm in love with the 40d engine anyway...but 380 mile journey over the weekend, cruising at 75/80mph with 20-30 miles of A/B roads saw less than half the tank used and a theoretic range of 800miles.

From a 170bhp 2-litre diesel, that would be good. For a 300bhp+ 3-litre it's just silly.

All major manufacturers make pretty much the same engine - staggering to think where technology can go to next.

[Rovinghawk]

Ares said:

From a 170bhp 2-litre diesel, that would be good. For a 300bhp+ 3-litre it's just silly.

Alternatively, it means a large fuel tank.

[Ares]

Rovinghawk said:

Ares said:

From a 170bhp 2-litre diesel, that would be good. For a 300bhp+ 3-litre it's just silly.

Alternatively, it means a large fuel tank.

70 litres - although brimmed to 0miles range only allows 65l.

[kambites]

That's about 50mpg isn't it? Reasonable enough, but hardly astounding for a modern car on a long cruise.

[Mr E]

kambites said:

That's about 50mpg isn't it? Reasonable enough, but hardly astounding for a modern car on a long cruise.

In a near 2 ton luxobarge with 300bhp and enough torque to pull your house it's pretty impressive.

[kambites]

Mr E said:

kambites said:

That's about 50mpg isn't it? Reasonable enough, but hardly astounding for a modern car on a long cruise.

In a near 2 ton luxobarge with 300bhp and enough torque to pull your house it's pretty impressive.

Weight makes little difference at constant speed and longer cars can have better aerodynamics, which helps. It's certainly a decent figure, but I wouldn't call it surprising.

I think I find the fact that BMW will sell you a petrol engine of similar power that will do over 40mpg under the same circumstances more impressive.

Edited by kambites on Monday 19th May 11:17

[SturdyHSV]

For reference, a 380mile journey of mostly cruising with a bit of A/B road would likely see my 70 litre tank completely depleted, with some serious fear induced coasting at the end...

Glad you're enjoying our diesel for what it's intended for

[anonymous-user]

It's less a reflection of the efficiency of the engine and more a reflection of the amount of optimisation that has occurred with the car and powertrain itself!


(ie, downspeeding, reduced parasitics (EPS, smart alternator, on-demand oil+water pumps etc, low drag & rolling resistance etc etc)

[Rawwr]

Mr E said:

In a near 2 ton luxobarge with 300bhp and enough torque to pull your house it's pretty impressive.

It'd be impressive if he was using all of it

[jon-]

If this was a real geek post we'd be talking actual MPG numbers, not distance per halfish an (unspecified sized) tank.

3/10.

[Captain Muppet]

I can get to my mate's house and nearly half way back on 3/8ths of a tank, if I cruise at a bit faster than most of the traffic but not so fast I don't still get overtaken a bit, according to my Mrs who was looking at the fuel gauge intermitantly.

I rekon that must be at least several miles to the gallon or litre, or was it kilometres? Either way it's damn impressive for a blue car, and it's not even metallic blue!

[J4CKO]

Sure its awesome, but if I could afford one, I wouldnt buy one, I would buy something that did 15 mpg and sounded like a Spitfire.

[Ares]

kambites said:

That's about 50mpg isn't it? Reasonable enough, but hardly astounding for a modern car on a long cruise.

Really? For a car that can keep up with a 997s coming off a roundabout?

What else better is? or what is astounding?

[Ares]

Rawwr said:

Mr E said:

In a near 2 ton luxobarge with 300bhp and enough torque to pull your house it's pretty impressive.

It'd be impressive if he was using all of it

Oh I do, and did. But not all the time. Bit too fond of my licence for that.

[Ares]

J4CKO said:

Sure its awesome, but if I could afford one, I wouldnt buy one, I would buy something that did 15 mpg and sounded like a Spitfire.

That's perhaps why you can't afford one

[AudiWurst]

kambites said:

I think I find the fact that BMW will sell you a petrol engine of similar power that will do over 40mpg under the same circumstances more impressive.

Which model/engine is that?

[schmalex]

The new hybrid in the 3 & 5 series looks interesting. I was speccing one up of their configuration tool yesterday and it is something like 306bhp and 42mpg.

I agree with the OP, the 40d in the 6 series is an excellent package

[thatdude]

jon- said:

If this was a real geek post we'd be talking actual MPG numbers, not distance per halfish an (unspecified sized) tank.

3/10.

Ok, here's some in depth stuff..

I have a civic 1.6 sport (2005). From the last service (about 500 miles ago now) I have managed to maintain an average 48 mpg (the computer calculates the average ever so optimistically...53 mpg over 300 miles was stated, but it turned out to be 49). Now, you might think this is due to it being recently serviced. Well, I offer more info...

The previous fill of oil was a semi synthetic 10w 40, which was in the car for about 6000 miles. I averaged around 42 mpg per tank. Somewtimes it got a little better with better fuels, but it wasnt really very good. With the fill previous to that (fully synth 5w30), it was the more satisfactory >45 mpg (usually around 47 mpg). Now, this is mostly motorway driving / commuting. I stick to the speed limit on the most part (95% of the time) and never exceed 80 mph (because its noisy).

I have also noticed that BP fuels return a lower MPG. Shell fuels are ok, but I seem to get the best economy from Esso fuels.

My current fill of oil is castrol 5w30 fully synthetic (always have used castrol)


So, MPG geeks....make of all that what you will. I dont know what my brother is doing with his pretty much identical honda civic but he isnt acheiving the mpg figures I do despite his claimed sedate driving and use of good oils...

in relation to the post then, in 10 years (the engine is 10 years old in design, probably older!) you can have impressive performance and it wont hurt the wallet so much when you fill up at the pump. Consider also that the ford ecoboost 1.0 engine makes a claimed 15 bhp more than my civic (125 vs 110) and has claimed better fuel economy (something like 62 mpg on the motorway?) then current tech is great

Edited by thatdude on Wednesday 21st May 17:05

[Ares]

schmalex said:

The new hybrid in the 3 & 5 series looks interesting. I was speccing one up of their configuration tool yesterday and it is something like 306bhp and 42mpg.

I agree with the OP, the 40d in the 6 series is an excellent package

Brings the question, unless the new price is a lot less than the 35d/40d variants, why would you go for it when the oil burner (just) tops the BHP, will offer greater torque and provide a (claimed) mpg almost 25% greater?

Not a great advert for hybrid tech......unless it offers 50+ miles of electric running?

[kambites]

Ares said:

Brings the question, unless the new price is a lot less than the 35d/40d variants, why would you go for it when the oil burner (just) tops the BHP, will offer greater torque and provide a (claimed) mpg almost 25% greater?

Refinement.

BMW may make very good diesel engines but they still sound, feel and rev like diesel engines. The diesel obviously has its place, but so does a petrol hybrid. I suspect the hybrid will sell well in the US where diesel passenger cars have never really taken off, too.

I'd tend to agree in general though - the one place diesels really make sense is in big, relaxed, motorway cruisers.

Edited by kambites on Wednesday 21st May 17:43