Consumption Confusion

[Snork2004]

My new GS300 Navigator (series II) is confusing me :duh:

According to the spec sheet this car has a 70 litre tank (I make this 16.7 galls give or take).

Over the last 1,000 miles the mpg shows as 28. Should be around 470 miles on a tankful then, right? Leave out 30 so as not to run dry and I would expect to be filling up at 440.

Never that simple though is it. The trip computer tells me that the range of the car is around the 400 mark when full. This then drops off to 30 after about 320 miles. Mysterious...

But then lo & behold, the car will only take around 55 litres to re-fill it - with a lot of effort to drip-feed the last 5.

What gives?

Have I got a small tank (I know how the guys in Tokyo like to play around with specifications)?

Is there some trick to filling the thing that I haven't mastered yet?

Am I carrying 15 "dead" litres of fuel? - would be a crisis in an F1 car.

Steve

[spitfire]

My new GS300 Navigator (series II) is confusing me :duh:

According to the spec sheet this car has a 70 litre tank (I make this 16.7 galls give or take).

Over the last 1,000 miles the mpg shows as 28. Should be around 470 miles on a tankful then, right? Leave out 30 so as not to run dry and I would expect to be filling up at 440.

Never that simple though is it. The trip computer tells me that the range of the car is around the 400 mark when full. This then drops off to 30 after about 320 miles. Mysterious...

But then lo & behold, the car will only take around 55 litres to re-fill it - with a lot of effort to drip-feed the last 5.

What gives?

Have I got a small tank (I know how the guys in Tokyo like to play around with specifications)?

Is there some trick to filling the thing that I haven't mastered yet?

Am I carrying 15 "dead" litres of fuel? - would be a crisis in an F1 car.

Steve

Hi Mate

I posted about this not long ago, I've got a GS mk 2 Sport with Sat Nav same as you and this is a real bugbear for me and really pisses me off.

The cruising range is a joke on the sat nav screen, for example if you do a steady 70 on the m/way you would expect the crusing range to recalculate its self and go up (as it does in BM's for example) but on the Lexus it stays the same.

I would like to know when you get to 0 or low fuel is displayed on the nav screen what is left in the tank.

You would expect the cruising range countdown to actually mean 0 miles left when it counts down and not say for example have another 60 miles worth of fuel left in the tank.

The mpg isn't great on the GS300 at the best of times and I have seriously thought of selling mine, the problem is and it is a real world problem is what do you go for after Lexus as the spec on them and reliablity will beat any car hands down, BM's, Merc, Audi included.

Jon

[maneesh]

Steve,

See here, as I brought this up recently too.

http://www.lexusownersclub.co.uk/forum/ind...showtopic=31708

Essentially, disregard any fuel computer in any car. These "displays" merely indicate information to the driver, and are not accurate. Think ballpark figure, rather than exact answer.

If your car is REALLY returning 28mpg on average, you should be getting approx 339 miles before you the low fuel light comes on.

However, I doubt you are getting anywhere near that unless you are spending all your time cruising on motorways. I calculate my own consumption, and am getting around 21mpg (80% stop start/20% B roads). That's with Tesco Super Unleaded too.

It's the way Lexus designed the car. It's got low gearing (for better acceleration), and it's a heavy beast too.

Ahhh, enjoy the ride and waft past 5 series and E class drivers that are doing without electric seats and electric steering wheels!

[spitfire]

Steve,

See here, as I brought this up recently too.

http://www.lexusownersclub.co.uk/forum/ind...showtopic=31708

Essentially, disregard any fuel computer in any car. These "displays" merely indicate information to the driver, and are not accurate. Think ballpark figure, rather than exact answer.

If your car is REALLY returning 28mpg on average, you should be getting approx 339 miles before you the low fuel light comes on.

However, I doubt you are getting anywhere near that unless you are spending all your time cruising on motorways. I calculate my own consumption, and am getting around 21mpg (80% stop start/20% B roads). That's with Tesco Super Unleaded too.

It's the way Lexus designed the car. It's got low gearing (for better acceleration), and it's a heavy beast too.

Ahhh, enjoy the ride and waft past 5 series and E class drivers that are doing without electric seats and electric steering wheels!

Maneesh, do you really think you are only getting 21 mpg, the read out on my nav screen reads approx 28-29 on the m/way and about 24 round town.

Usually reads 26 on average.

I put £40 in this week and the nav range stated 240 miles so 60 miles to £10 so I dont know how accurate the computer is on the car.

What do you recon I would get for a 2000 300 Sport with nav in platinum ice with 95k on the clock ?

[maneesh]

Spitfire,

Yes, that's what I'm getting. I'm calculating using the miles I'm doing between fillups, so pretty accurate. Your satnav screen is probably OVER estimating your mpg. Calculate the figures yourself and tell us what you are getting.

I've seen some 2000 GS300 sports recently sell on eBay for around 8 grand up to 8,750.

[spitfire]

Spitfire,

Yes, that's what I'm getting. I'm calculating using the miles I'm doing between fillups, so pretty accurate. Your satnav screen is probably OVER estimating your mpg. Calculate the figures yourself and tell us what you are getting.

I've seen some 2000 GS300 sports recently sell on ebay for around 8 grand up to 8,750.

Dont say its over calculating its bad enough showing below 30 :D

[Ahhhh__Aristo]

It's a circa 1600kg car, with 6 cylinders and 3000cc capacity, I'd count 28mpg a miracle.

21mpg sounds alot more realistic (the supras produce that sort of mpg and are a bit lighter I believe)

I only get around 16mpg

Easy enough to work out manually what your getting.

[Snork2004]

OK. Another tankfull (ish) goes by and the thot plickens...

At 305 miles the low fuel light came on and the cruising range showed as 30.

At 335 miles the cruising range had dropped to 14.

At 363 miles the cruising range finally dropped to 0.

Filled up 6 miles later - 369 miles @ a reported 28.6 mpg (for the tankfull).

Took 62 litres - right up the neck of the tank.

Capacity is supposed to by 75 litres - there's definitely a family of algerians living in the tank.

Calculated mpg is 27.

Buggerdifino.

Saw a Volvo S80 T6 driver this morning - brand new, obviously just picked it up - and the look on his face when I parked next to him was a picture - the guy was green and walked away with his shoulders slumped around his knees.

Who needs good fuel consumption when you can have moments like that.

Cheers

[spitfire]

OK. Another tankfull (ish) goes by and the thot plickens...

At 305 miles the low fuel light came on and the cruising range showed as 30.

At 335 miles the cruising range had dropped to 14.

At 363 miles the cruising range finally dropped to 0.

Filled up 6 miles later - 369 miles @ a reported 28.6 mpg (for the tankfull).

Took 62 litres - right up the neck of the tank.

Capacity is supposed to by 75 litres - there's definitely a family of algerians living in the tank.

Calculated mpg is 27.

Buggerdifino.

Saw a Volvo S80 T6 driver this morning - brand new, obviously just picked it up - and the look on his face when I parked next to him was a picture - the guy was green and walked away with his shoulders slumped around his knees.

Who needs good fuel consumption when you can have moments like that.

Cheers

Snork, so you recon your tank could of had 13 litres in it when you filled up ?

So if you carried on till you actually ran out how many miles do you think you could of gone on for ?

What was the cost of filling up ?

[maneesh]

It's a circa 1600kg car, with 6 cylinders and 3000cc capacity, I'd count 28mpg a miracle.

21mpg sounds alot more realistic (the supras produce that sort of mpg and are a bit lighter I believe)

I only get around 16mpg

Easy enough to work out manually what your getting.

1720kg to be exact. Only 95kg less than LS400 (according to Lexus UK website). It's a thirsty engine as it's an older design. 28mpg is possible, but on long motorway runs. I got 26mpg doing a long run down to Cornwall.

Capacity is supposed to by 75 litres - there's definitely a family of algerians living in the tank.

Calculated mpg is 27.

Saw a Volvo S80 T6 driver this morning - brand new, obviously just picked it up - and the look on his face when I parked next to him was a picture - the guy was green and walked away with his shoulders slumped around his knees.

Who needs good fuel consumption when you can have moments like that.

Cheers

80 litre tank actually. Errr, good fuel consumption would be useful as well as the admiring glances!!!!

Interestingly, everyone at work thinks I'm loaded just because I've got a 7 year old GS! I think it's the xenons in the office car park that make people think it's more expensive than it actually is!! To be fair, the S80 has the best car seats I've ever experienced.

Snork, so you recon your tank could of had 13 litres in it when you filled up ?

So if you carried on till you actually ran out how many miles do you think you could of gone on for ?

What was the cost of filling up ?

Well, assuming 27mpg consumption, his tank would run dry after a grand total of 475 miles. That's 106 miles further than he did. Right, who's going to experiment with running the tank to empty?

[ColinBarber]

80 litre tank actually. Errr, good fuel consumption would be useful as well as the admiring glances!!!!

I believe the series II has a 75l tank. The series I had an 80l tank.

[danielbroad]

One interesting thing you discover when you convert to LPG, on SatNav MK2 GS's the fuel gauge and cruising range drop even if you're not actually using any petrol, it works on kind of a "i know how much fuel is going into the engine and i know how much i had in the tank, so this is how much i should have".

You can't rely on the guage or the computer to tell how much petrol there actually is in the tank, very bizarre.

Daniel.

[Snork2004]

OK. Finally did the deed - Full to empty with a spare can in the boot.

On filling the cruising range showed as 432.

After 100 miles, cruising range had dropped to 335 - pretty much in line.

After 120 miles, cruising range dropped to 210 - wha?

Kept going.

Full light finally came on at 380 - range now 30 miles.

The last 30 miles are always pretty forgiving so it took until 425 for the cruising range to fall to 0.

Kept going.

Finally made it to 468 miles before she started to splutter.

Interesting to note that adding the 6 litres from the petrol can did not reset the distance after re-fuelling or the mpg - obviously below the minimum that whatever sensor that is inside the tank can read.

PS. Took 10 more miles to get to a garage and then 70 litres to fill her back up again.

Before the questions start:

Of the 468 miles, approx 250 (Leicester/Swindon/Nottingham) were Motorway - 75-85 ish (or stationary)

Of the rest, mixed driving, mainly Grantham - Nottingham centre.

Only problem now is that I can't remember why I set out to do this!

Going for a lie down now.

[maneesh]

PS. Took 10 more miles to get to a garage and then 70 litres to fill her back up again.

So you are saying you got around 30mpg on that tank. Bloody impressive!

[RX-Men-8]

Excellent!! Proof that the boardcomputernanny is manipulating you to go fill up early. Every time I think the IS200 is almost empty I can only fill up 60l, so there was another 50odd miles to go.

RX-Men-8