2010 C30 1.6 start/stop fuel economy query - Page 2

80p · Jul 27th, 2010, 14:35

As I've said before, our C30 S/S has been doing great mileages and getting slightly better at 5k miles. It is averaging 73.5mpg and I've had two trips at 91mpg. The best sight was last week, after a fill up, when the trip showed 1135 (yes, one thousand, one hundred...) miles to empty tank.

The tyres are at eco pressure (mahogany hard) and no A/C. Oh yes, and driving like a nun with 11 points, aka legally, everywhere. So the Volvo numbers are real. They do use trick drivers on the rolling road and the EU cycle is pretty benign.

Jo_Jo · Jul 28th, 2010, 14:33

Quote:

Originally Posted by 80p

As I've said before, our C30 S/S has been doing great mileages and getting slightly better at 5k miles. It is averaging 73.5mpg and I've had two trips at 91mpg. The best sight was last week, after a fill up, when the trip showed 1135 (yes, one thousand, one hundred...) miles to empty tank.

The tyres are at eco pressure (mahogany hard) and no A/C. Oh yes, and driving like a nun with 11 points, aka legally, everywhere. So the Volvo numbers are real. They do use trick drivers on the rolling road and the EU cycle is pretty benign.

Wow 80p that is amazing!! We'll start driving with no aircon on, any other tips other than driving smoothly (no heavy foot :-( ) and keeping a general eye on the actual mpg whilst going along? As you're at 5k miles and we are at 11k+ that really is interesting.

80p · Jul 31st, 2010, 15:21

Hi Jo_Jo Yes, the car is amazing us too. On the economy aspects, one can look at it as two separate issues - energy demand and energy supply. The energy demands are tyre rolling drag, aero drag plus the need to run the vehicle systems. Tyre drag does not hardly change with speed, so it's down to car weight, type of tyre and inflation pressure. Eco pressure setting is not too comfy, but it freewheels like a push bike. Aero energy goes up with the square of the speed, so 4 times higher at 80mph than 40mph so bad news.

Brakes turn fuel (that you've paid for) into heat. A side effect is slowing the car too. So braking is always bad, coasting is perfect. When you need to brake, try to use the lower gears to spin up the alternator to at least save a bit of the kinetic energy into the battery. That way the engine, using your fuel, will not have to generate it next time. BMW have done a great job on this micro-regen stuff. If you've seen the annoying ad, Audi call it 'recuperation'....

Speed & tops-of-hills both have stored energy that is your stored fuel. It is perfectly efficient storage as you get 100% back, unlike a Prius that only gets 75% back out of its hybrid battery. So it needs to be used, not braked away to heat.

On the energy supply from the engine, the plan is to operate the engine at the maximum efficiency point. This VW TDi page, the bottom 2 graphs:
http://forums.tdiclub.com/showthread.php?t=208125
has a typical fuel map for a modern turbo diesel.

Engine revs across the bottom, torque (sort of) up the side with contour lines of fuel efficiency. The plan is to operate around the 197 number or 42% thermal efficiency. So heavy foot is the right thing to do, despite other comments, as it is close to full torque, but low revs. The C30 S/S has change up arrows to keep you in the 1,000 to 2,000 rev band. If you stick to legals, it need will 2,150 for 70mph. Otherwise the target is the engine revs starts with a 1 and fuel average starts with a 7.

Complicated, but hard tyres, no A/C, no braking (hardly), low revs, full welly when accelerating, high gear, modest speeds = 70+mpg.

Good Luck!

PS Oh no, more numbers!
Divide your mpg into 283 to give l/100km metric fuel consumption
Divide your diesel mpg into 7500 to give g/km of CO2
Divide the g/kWh number into 8400 to give % thermal efficiency.

72dudes · Jul 31st, 2010, 15:43

Are you a Science Teacher 80p?? Lol

Good stuff.

shaymus · Aug 6th, 2010, 13:18

This is an interesting thread. I also live in the Fens, only a few miles from March and drive a 2.0d S40.

Driving to Huntingdon each day gives me 54mpg, average speed is 40mph, per the computer. On longer runs, (a1 & a14 & M11 etc) and resetting the computer I'm averaging well over 60mpg. These figures are also borne out by manual caluclations. Use Shell V-power at the moment, but thinking of trying the new, more efficient stuff. Anyone heard if this is any good or not?

Jul 27th, 2010, 14:35	#11
80p New Member Last Online: Feb 17th, 2015 17:55 Join Date: Dec 2009 Location: London	C30 economy As I've said before, our C30 S/S has been doing great mileages and getting slightly better at 5k miles. It is averaging 73.5mpg and I've had two trips at 91mpg. The best sight was last week, after a fill up, when the trip showed 1135 (yes, one thousand, one hundred...) miles to empty tank. The tyres are at eco pressure (mahogany hard) and no A/C. Oh yes, and driving like a nun with 11 points, aka legally, everywhere. So the Volvo numbers are real. They do use trick drivers on the rolling road and the EU cycle is pretty benign.

Jul 31st, 2010, 15:21	#13
80p New Member Last Online: Feb 17th, 2015 17:55 Join Date: Dec 2009 Location: London	C30 fuel burn Hi Jo_Jo Yes, the car is amazing us too. On the economy aspects, one can look at it as two separate issues - energy demand and energy supply. The energy demands are tyre rolling drag, aero drag plus the need to run the vehicle systems. Tyre drag does not hardly change with speed, so it's down to car weight, type of tyre and inflation pressure. Eco pressure setting is not too comfy, but it freewheels like a push bike. Aero energy goes up with the square of the speed, so 4 times higher at 80mph than 40mph so bad news. Brakes turn fuel (that you've paid for) into heat. A side effect is slowing the car too. So braking is always bad, coasting is perfect. When you need to brake, try to use the lower gears to spin up the alternator to at least save a bit of the kinetic energy into the battery. That way the engine, using your fuel, will not have to generate it next time. BMW have done a great job on this micro-regen stuff. If you've seen the annoying ad, Audi call it 'recuperation'.... Speed & tops-of-hills both have stored energy that is your stored fuel. It is perfectly efficient storage as you get 100% back, unlike a Prius that only gets 75% back out of its hybrid battery. So it needs to be used, not braked away to heat. On the energy supply from the engine, the plan is to operate the engine at the maximum efficiency point. This VW TDi page, the bottom 2 graphs: http://forums.tdiclub.com/showthread.php?t=208125 has a typical fuel map for a modern turbo diesel. Engine revs across the bottom, torque (sort of) up the side with contour lines of fuel efficiency. The plan is to operate around the 197 number or 42% thermal efficiency. So heavy foot is the right thing to do, despite other comments, as it is close to full torque, but low revs. The C30 S/S has change up arrows to keep you in the 1,000 to 2,000 rev band. If you stick to legals, it need will 2,150 for 70mph. Otherwise the target is the engine revs starts with a 1 and fuel average starts with a 7. Complicated, but hard tyres, no A/C, no braking (hardly), low revs, full welly when accelerating, high gear, modest speeds = 70+mpg. Good Luck! PS Oh no, more numbers! Divide your mpg into 283 to give l/100km metric fuel consumption Divide your diesel mpg into 7500 to give g/km of CO2 Divide the g/kWh number into 8400 to give % thermal efficiency.

Jul 31st, 2010, 15:43	#14
72dudes Junior Member Last Online: Jul 5th, 2015 14:31 Join Date: Jun 2010 Location: Bury St Edmunds	Are you a Science Teacher 80p?? Lol Good stuff.

Aug 6th, 2010, 13:18	#15
shaymus New Member Last Online: Mar 8th, 2024 19:15 Join Date: Apr 2009 Location: Cambridge	This is an interesting thread. I also live in the Fens, only a few miles from March and drive a 2.0d S40. Driving to Huntingdon each day gives me 54mpg, average speed is 40mph, per the computer. On longer runs, (a1 & a14 & M11 etc) and resetting the computer I'm averaging well over 60mpg. These figures are also borne out by manual caluclations. Use Shell V-power at the moment, but thinking of trying the new, more efficient stuff. Anyone heard if this is any good or not?

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