Mpg

spkennyuk

Member
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5,930
I am a bit dissappointed about the fuel economy of the 4200. My 550 is not any thirstier. I think some of the reason for it is the 7500 redline, which means the car is low geared even in 6th. My 2002 M3 gets about 30 mph. when cruising at 90 kph.!! Even With my boat behind it, it uses less fuel than the Maserati. Something is wrong in the engines mapping......

The 2002 m3 is a V6 3.2 ltr which is why its more economical for the same era of car. V8 4.2 ltr will use more fuel V12 like an Jaguar xjs although an earlier car era would use more fuel again.

You really cant compare a M3 and 4200 as similar cars or specs to expect similar mpg.

If it was possible to switch 2 cylinders off on a 4200 cruising at 90 kph then your fuel economy would be around the 30mpg.

V6 being a lighter lump and more econimical is why manufacturers have dropped v8s and switched to v6 turbos. The ones still using v8, v10 and v12s tend to employ systems to turn off cylinders when not required to improve emissions and mpg.
 

F456M

Member
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124
The 2002 m3 is a V6 3.2 ltr which is why its more economical for the same era of car. V8 4.2 ltr will use more fuel V12 like an Jaguar xjs although an earlier car era would use more fuel again.

You really cant compare a M3 and 4200 as similar cars or specs to expect similar mpg.

If it was possible to switch 2 cylinders off on a 4200 cruising at 90 kph then your fuel economy would be around the 30mpg.

V6 being a lighter lump and more econimical is why manufacturers have dropped v8s and switched to v6 turbos. The ones still using v8, v10 and v12s tend to employ systems to turn off cylinders when not required to improve emissions and mpg.

That is in fact not 100% true. The M3 is a inline six cylinder engine and has a redline at 8.300 rpm, so even more of a hgh rev enine than the Maserati. My 550 Maranello With 5,5 liter V12 Ferrari is not more thirsty than the Maserati!And my 2003 Chevrolet Avalanche 5,3 l V8 is more economic. That car has a weight of 3 tons with full tank and me onboard + has considderably more drag due to its size! The Maserati should be better on fuel consumption. I also have a 4,0 l Jag XK8 which is almost as good as the M3 at a steady speed. At 130 kph., it zips 9 liters per 100 kms.... I bought the Maserati as a more user friendly car which can be parked utside overnight and so on, as a more "user friendly" Ferrari alternative + has 4 seats so I can still drive italian high performance and save milage on the 550 in everyday life. Truth is, the 4,2 Maserati is about the same horrendous gas guzzler as the V12!! The 550 use 13l / 100 km. on a steady 100 kph, and 20 l on a steady 200 kph. and about 20-30 liters every 100 kms on city driving. It drains the fuel tank in the city... It takes about 105 liters so can reach about 350 kms of city driving on a full tank. While the Maserati has a much smaller tank while almost the same consumption......
 

spkennyuk

Member
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5,930
My appologies i meant an inline 6 for the M3.

The UK tested figures for the Ferrari 550 and 4200 for the urban/ combined / extra urban show the 4200 is more economical under said test conditions. Not a huge amount but the 4200 gains mpg on both the urban and extra urban testing. We all know that real world driving results will be different as we can not replicate the test conditions on public roads.

Take your 550 figures of 13ltr at 100kph that equates to 21mpg at 62mph. The figures achieved on my 4200 at 75mph was 22 mpg. If i had reduced my speed to a constant 62 would i have got 23 or 24 mpg yes i expect so.

Could any cars mpg be improved with a remap. Yes if its done properly as you can tune the map to the quality of fuel available in each country and also tune the map to the specific car.

If you compare the Ferrari 360 against the 4200 then mpg figures i expect would be almost identical. Even though the Ferrari is around 600cc smaller in capacity.

The future super car engine line ups will be by the looks of it v6 turbos instead of v8s and some v12s.

V10,V12s and W16s will all employ cylinder deactivation.

3rd option being petrol / electric hybrids.

All for the purpose of reducing emissions and improving mpg. I think the last of the V8 will be made in the next few years unless somebody decides to use cylinder deactivation technology to have it switch between 4 and 8 cylinders.

What is 100% true is we should all just drive them and enjoy them without worrying too much about the mpg and just enjoy the V8 cars or any peteol cars while we still can. :)
 

midlifecrisis

Member
Messages
16,102
To change the thread slighty (ie to deliberately and openly create thread drift, unknown on these parts) .

Is it possible to remap an engine to introduce 'cylinder deactivation'? Or would some sort of mechanical modification be required to prevent excessive wear and tear due to the lumpiness?

I think a few people would be interested to improve mpg and improve the range of the vehicle when cruising through France.
 

midlifecrisis

Member
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16,102
Oh and I've had 27 mpg when going through a 50 mph average speed camera stretch of a motorway. One thing I have noted is that the average mpg sticks to certain numbers 12.7, 14.1 etc not 14.0 and I do seem to remember it being in US Gallons according to the manual not UK Gallons therefore you can multiply the figure by 1.2 therefore 17mpg is actually a whopping 20mpg!
 

mjheathcote

Centenary Club
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9,033
This is the answer of course!

[video=youtube_share;58IkmPK6ikc]http://youtu.be/58IkmPK6ikc[/video]
 

spkennyuk

Member
Messages
5,930
To change the thread slighty (ie to deliberately and openly create thread drift, unknown on these parts) .

Is it possible to remap an engine to introduce 'cylinder deactivation'? Or would some sort of mechanical modification be required to prevent excessive wear and tear due to the lumpiness?

I think a few people would be interested to improve mpg and improve the range of the vehicle when cruising through France.

Even if it could be done you would have no way of turning the other clinders back on without introducing some electronics into the equation.

The other thing that springs to mind with the 4200 engine is the firing order of spark plug/pistons is a bit odd. So getting the smoothest cycle of 4 cylinders 2 from each bank may also need a mechanical change to the crank and cam shafts.

In short i think the engine would really have to be designed for cylinder deactivation from the ground up. Adding the ability later seems logically to need some serious electro and mechanical changes.

Or just unplug 4 HT leads ! Lol :)
 

midlifecrisis

Member
Messages
16,102
Even if it could be done you would have no way of turning the other clinders back on without introducing some electronics into the equation.

The other thing that springs to mind with the 4200 engine is the firing order of spark plug/pistons is a bit odd. So getting the smoothest cycle of 4 cylinders 2 from each bank may also need a mechanical change to the crank and cam shafts.

In short i think the engine would really have to be designed for cylinder deactivation from the ground up. Adding the ability later seems logically to need some serious electro and mechanical changes.

Or just unplug 4 HT leads ! Lol :)

BUt if you switched off the injector, keep the spark, that should do it.
 

spkennyuk

Member
Messages
5,930
Oh and I've had 27 mpg when going through a 50 mph average speed camera stretch of a motorway. One thing I have noted is that the average mpg sticks to certain numbers 12.7, 14.1 etc not 14.0 and I do seem to remember it being in US Gallons according to the manual not UK Gallons therefore you can multiply the figure by 1.2 therefore 17mpg is actually a whopping 20mpg!

From memory the averagr mpg goes up or down in 0.3 mpg at a time.

Its UK gallons as well. I think there is a setting in either the info hidden menu or the Sd3 menus that allows it to be set for the correct market.
 

Zep

Moderator
Messages
9,110
The main theory in cylinder deactivation is that when a cylinder is deactivated it draws in a partial charge of fresh air (with no fuel) on the inlet stroke and then both the inlet and exhaust valves are disabled by a mechanical device in the valve train. Then you effectively have an air spring in the deactivated cylinder, it is compressed on the upstroke of the piston and the energy is then released back to the crank on the downward stroke. This way the pumping losses are negated which is actually the bit you feel when you have a misfire. If you were able to achieve this (you aren't without new cylinder heads) you would also then need a very clever ECU to increase throttle opening and revise the ignition timing to increase the torque from the cylinders that remain instantaneously to prevent the transition being very lumpy indeed.

The short version of this answer is No....
 

FIFTY

Member
Messages
3,100
I am a bit dissappointed about the fuel economy of the 4200. My 550 is not any thirstier. I think some of the reason for it is the 7500 redline, which means the car is low geared even in 6th. My 2002 M3 gets about 30 mph. when cruising at 90 kph.!! Even With my boat behind it, it uses less fuel than the Maserati. Something is wrong in the engines mapping......

The E46 M3 when cruising is economical compared to the 4200 I thought this was quite common knowledge to be honest. Did you look at the mpg stats before buying? I think the majority of people know what they are getting into (a 10-20 mpg car) but on occasion we see threads like this where a new owner complains about the economy

As you mentioned gearing is a factor, although i haven't tried it I am fairly certain these cars are geared to go to their top speed i.e. 176mph at 7500rpm/red line rather than having an electronic limiter... this explains the high gearing... the only other car I have had like this was my lexus is 200 which bad a 2.0 inline 6 with 6spd manual and similarly that drank fuel as it was at 3500rpm cruising at 65mph
 

conaero

Forum Owner
Messages
34,593
Oh and I just had a flashback to our economy run into Claremont Ferrand. That wasn’t close at all

Vapours (French accent engaged)

Didn’t we get something silly like 400 miles out of a brimmed to drained tank?

Oh and I’ve already forgotten to get that trip mode you showed me on the NAV.
 

F456M

Member
Messages
124
No I don't really care that much about fuel economy, but after I bought the M3 I started to wonoder WHY is it like this....? That car has a weight of 1700 kg as it is a cabriolet, so it is not much smaller or lighter. I am used to run speedboats With from 2 up to 4 American V8s onboard, so for me the car hobby is quite "economical" after all. But when thinking of it, if I drive the 4200 and reach Switzerland from Norway, on the same amount of petrol with the M3, I can og all the way down to Saint-Tropez!! So it definately has an impact wether I like it or not... Another factor importat for the efficiency (as I have ben told) is the bore x stroke ratio of an engine. The bore is 87 mm. whilst the stroke is 91! So the opposite of the Maserati which is very over-quadratic at bore 92 x 79,7 mm. This means that the BMW has a much better combustion and has more time to burn the fuel. Correct me if I am wrong. I do love both cars. The performance of the Maserati is superior to the BMW, even though both are really fast.
 

Zep

Moderator
Messages
9,110
Vapours (French accent engaged)

Didn't we get something silly like 400 miles out of a brimmed to drained tank?

Oh and I've already forgotten to get that trip mode you showed me on the NAV.

It was something like that, i seem to recall it was something like 396 and we lost the bottle to go the extra miles. I can't remember that mode in the Nav either
 

FIFTY

Member
Messages
3,100
What octane fuel do you use? I try to stick to Shell 99 nitro plus (or whatever they call it now)... I once used 95 octane for a motorway journey and I am not sure it is because the ECU had adapted to 99 octane but it annihilated 3/4 of a tank on a 180 mile journey... I usually get 300 miles from a tank and I I don't drive that gently
 

spkennyuk

Member
Messages
5,930
Vapours (French accent engaged)

Didn’t we get something silly like 400 miles out of a brimmed to drained tank?

Oh and I’ve already forgotten to get that trip mode you showed me on the NAV.

I baulked at 420 in mine as i didnt want the fuel pump scrabbling round for dregs. It took 82 liters to brim fill again so in theory there was still around 6 liters in the tank.

The opposite end of the scale is the lowest i have had with mostly town and spirited driving is 300 miles to a tank. Which is still 15.5 mpg.

I really dont think 15 to 22 mpg range for a v8 with a 4.25 ltr displacement from the 2003 to 2007 ish time period was either low or much different to anything else of the same or similar displacement and cylinders. The M3 of the same time period had 1ltr less displacement.

Xk8 of the same era shows 16/18/23 mpg for the urban / combined / extra urban tests which is probably the closest comparison being a V8 and 4 liter displacement. Odly enough almost the same official mpg figures as the 4200.

Final gearing of the compared cars would effect the figures as would tyres , overall weight and many other factors. Where the rev limiter is has no bearing unless your driving on the limiter. Even then its going to reduce fuel economy as your pushing more fuel through at higher revs. We can do 70mph in any gear between 3rd and 6th. We put it in 5th or 6th to get better fuel economy by reducing the revs.

Running at lower revs is more economical on any engine. Its why diesels are much more economical for comparative displacements.

The wankel engine in an Mazda Rx8 is a 1.3ltr displacement in a small light car. Rev limiter 9000 rpm but still only get around 20mpg. Take the 1.3ltr diesel punto rev limiter around 4k and your looking around 65 mpg.

Two totally different engine and rev ranges but they do have one thing in common. The lower the revs the more mpg you will get at any given speed.

The 4200 and GS produced average mpg for the same / similar sized v8 engines of the day in a similar size / weight of vehicle.

If you took the cars out of the equation and just had the various 4 ish ltr v8 engines of the day on a test rig with the same gearbox and axle set up but no car then i suspect the mpg figures would be very similar for all the different v8 engines tested.
 

spkennyuk

Member
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5,930
What octane fuel do you use? I try to stick to Shell 99 nitro plus (or whatever they call it now)... I once used 95 octane for a motorway journey and I am not sure it is because the ECU had adapted to 99 octane but it annihilated 3/4 of a tank on a 180 mile journey... I usually get 300 miles from a tank and I I don't drive that gently

The 4200 is mapped to run on 95 octane fuel which i use most of the time. Every 4th or 5th tank i put 97 or 99 octane rated fuel in. If im on a track day then it has 97 or 99 rated fuel in.

Is there much difference. Possibly slighter better response from the throttle but the cars are not mapped to take full advantage of a higher octane fuel than 95 so any gains are going to be minimal.
 

CatmanV2

Member
Messages
48,543
Put 99 in my 4200 once. Absolutely no difference at all. The only time I've noticed a difference using premium petrol was on my old Ducati Monster that had a significant carb icing issue. That fixed it, but I'm bloody sure it was nothing to do with octane, but more to do with the additives.

My GT gets a regular diet of Tesco's finest 95 octane Momentum :D

C
 

spkennyuk

Member
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5,930
Put 99 in my 4200 once. Absolutely no difference at all. The only time I've noticed a difference using premium petrol was on my old Ducati Monster that had a significant carb icing issue. That fixed it, but I'm bloody sure it was nothing to do with octane, but more to do with the additives.

My GT gets a regular diet of Tesco's finest 95 octane Momentum :D

C

I honestly think its more placebo effect using a higher octane rated fuel in a car that isnt mapped for it. Yes im sure the additives help clean the fuel system which is why i chuck a tank full in from time to time.

You expect the car to be a little quicker and sharper having just paid about 50p a gallon more for the higher octane fuel. You then pay more attention to the responce and speed of the car and probably push a little harder to test if it is. Reality is its slower as your now lugging an extra 80 kg / ltrs of fuel around that were not in the car when you pulled into the garage on empty.