petrol usage differences

[Maat1985]

i currently own 2 280se's in not so good shape.....

at the moment i am just beggining to look for a 450 to replace the 2 cars i own currently and i was just curious as to what the fuel economy differences are

both freeway driving and city driving.....

hope you guys can help......

[flutes]

Maat I commute from St Ives to Rushcutters Bay most weekdays, usually in peak-hour or close-to-it times.

It's pretty rare that the runs in are straight and fast but they have been over the past few weeks with everyone on holidays - I've been getting roughly 15L/100kms, which isn't amazing.  This doesn't change a hell of a lot from the still-on-the-freeway-but-might-as-well-be-city-driving of busier times,  where I find I'm getting anywhere 16 to 20L/100kms.  This is largely due to how heavy I am on the right foot...

[TJ 450]

It's 17-20L per 100km for my 6.9 depending on how it's driven. I don't reckon there's much difference at all.

Tim

[Maat1985]

practically the same as what i was getting from my 280

[goldacre]

Just back from Busselton in the 450SEL and recorded the following fuel consumption:

Rockingham (fueled up on PEAK brand premium) to Busselton via new Forrest Hwy = 13.7 liters per 100klm  (sitting on mostly 100kph with A/C on and boot full of boat stuff)

Busselton (fueled up on Caltex Vortex 98 and added Morey fuel conditioner) to PEAK fuel station about 20 klm East of Northam on Great Eastern Hwy = 16.3 liters per 100klm  (sitting on mostly 110kph [minimum] with A/C on and boot full of boat stuff, outside temp 47oC)

Pretty happy with those figures but what i have noticed with the 450 is that if you can bear driving at 100kph the fuel economy is good.

Tune up wise i have replaced the ignition system with a new Coil, distributor cap, rotor, BERU ignition leads and generally reviewed and re plumbed old vacuum lines)

Next mechanical event is new injectors and seals, WUR overhaul (MB Spares can do this for about AU$270) and timing chain replacement with sundries so will use the above as the benchmark to evaluate fuel economy in the future. 

G

[s class]

M110 fuel consumption has been discussed a lot here on the forum in the past.  I think its safe to say that general consensus is that anything over 15L/100km indicates something is not right.  My 280SE is in a good state of tune, and I can cruise much higher than 100km/h with 4 people plus luggage, and still get 15L/100km.  Bear in mind that even slight errors in the valve clearances leads to a significant deterioration in economy.  Likewise, even subtle WUR problems or subtle mixture adjustment errors will lead to terrible economy.

[TJ 450]

Wow, 13.7 litres is a nice figure Goldacre.

I drove the 6.9 180km today and I must say, the needle didn't move much. Maybe it was the high ambient temperature? Not to get too off-topic, but 47oC is excessive... how did the cooling system behave in those conditions? Mine is ok, but it got up to 95oC or a tad off 100oC on today's run up to Yanchep and the Northern Beaches.

Tim

[goldacre]

Hi Tim, I use the formula of divide total Klm by 100 (move decimal point 2 places to the left) then divide that sum into total liters used.
Personally i was surprised at the 13.7 return but i can say i top the fuel tank up to the most near full position possible at all times 

The temperature issue was amazing, i will say that i have installed a brand new Radiator ( X Ebay 2007), water pump, thermostat, fan clutch, Flow Kleen coolant and new hoses and this is what happened...

Temperature sat at 78-79 degrees C, until i got to Mandurah then crept up to 81 degrees C; up into the hills she got to 85 ish then when idling for 10 min at the pi(ss)t stop she went up to 90 degrees C, (10 klm before Goomalling) i was very happy with that result  (read - releaved)

I have a replacement temp sender to install (just in case  ) But i have used the food grade infra red temp gun on the hoses and they repeat the figure mentioned.

I will confess that i was surprised at the 13.7 liters per 100 but did use the above formula to get the readings mentioned.  Anyone driving the new Forrest Hwy will know the cross wind is bad and it was blowing from the West at the time i was driving South so not really a bad head wind, mind you the drive back to the wheatbelt was the same  .

G

[pompy]

I think I was rather lucky with my '79 350 SE. My best ever was 12,3l/100km after a 300km highway stretch at high altitude at a genuine 120km/h - with only me as a passenger, but with all my earthly belongings which resulted in the car having a take-off stance. No a/c at that stage.
On highway drives I almost always saw 300km come up when the fuel guage hit the halfway mark.
That said, my cruising speed was always between 120 and 140km/h.
Also, I think even though it was properly tuned, it ran a bit lean as even with LRP the flared exhaust pipe edges would have an orangy tint after a long drive.

Ave consumption was 14,5l/100km. I never had the chance to do real city driving, although short 5km trips to town during very cold winter weather resulted in @ 19l/100km - don't think it ever warmed up properly.

[flutes]

s class from your comments I would seem to have a problem with my 450 - given in regular driving the best I get is about 16L/100kms.  Would the drop in efficiency also be causing a comparable and noticeable reduction in performance?

[s class]

flutes, my comment about 15L/100km being the 'boundary' applies to the 280SE 6 cyl.  The 450 does use more.  I don't have a 450W116, but in the 450 R107, I'd be very happy if I did as well as 16L/100km.

[flutes]

Ahh - I skipped the bit where you mentioned it was for an M110.

Tim I'm surprised at your fuel consumption with the 6.9 - is that typical of M100s?

[s class]

Link

[flutes]

Wow - that's an impressive run.

I assumed that 6.9s would be thirstier on the fuel than that - perhaps I should upgrade!

[pompy]

Wow, s class, that must have been an enjoyable trip. Its always great to drive these wonderful cars over long distance - an epic journey