Typical Is300H Motorway Fuel Consumption

[j87mcn]

Hi all, first post...

Recieved my IS300H on Wednesday, so far I’ve only really had one motorway journey where it hovered around 39 mpg at 70 mph until I hit a load of 50 mph stretches where I managed 45 mpg.

I look at some of the figures banded about and I’m 5 to 10 mpg less than what others seem to get. I know the engine needs time to loosen up a bit, but I’m a little disappointed with the figures in comparison. 

Driving in eco mode, taking it easy on the accelerator, staying within the eco band on the dash 90% of the time...

Any thoughts/tips?

[gt03raf]

the cold weather will impact it by at least 5 mpg. It will get better as the car loosens up and as the weather warms up.

If i sit at 70 on the motorway i can see 45-50mpg. at 55-60 mp i have managed to 55-60mpg

Andy

[ColinBarber]

What size wheels to you have? What pressure are the tyres?

Weather won't make a big difference on a motorway, most of the drop off in cold temperatures is due to the engine getting up to temperatures and lower speed driving. 

 

[j87mcn]

I did consider the temperature but it hasn’t been that bad the last few days...

17”, 38 psi rear and 35 psi front, checked them earlier today.

[Carl1983]

I have an f sport and mainly do motorway driving around 350 miles a week. In the summer I average 51 mpg with 18 inch wheels. Currently I have winter alloys on with winter tyres, they are 16 inch and today I averaged 56mpg. Yours do appear abit low to be honest  

[Mr Vlad]

What a good thread this is. My own experience is @70mph my average is knocking on the door of 50mpg.

My commute is 14 Mikes one way consisting of 1 mile at 30 mph then 2 miles accelerating uphill to 70 mph then a further few Mikes at ahem 80 mph then I'm on a 40 mph limit road for a couple miles on Battery. Then back on the motorway at 70 then an A road at 30 mph. Going to work at 430 am I'm getting 50 to 52 mpg.

On the way home at about 3pm I do use the sport to enter the motorway from the traffic lights and I Do floor it to near 80. When on the 40 road I'm on Battery most of the time. My average falls to between 42 and 44 mpg. I'm chuffed wirh that and it' better than the diesel fords I've had lol.

[BigChange]

Ganzoom, I would be interested to know what reliability issues you had with your 3 series.  In the 16 years  that I owned two 320D, I had 2 blown turbos (fortunately both in Germany) but otherwise no problems.  Not that the turbo repairs were "minor".  Was I just lucky with the rest?   And not that I'm thinking of going back.!

[Roscobbc]

My IS300H Exec's contract ran out November - new wheels now are a plug-in Hybrid BMW 2 Series Active Tourer. Yes, its a BIK thing, and I know - hardly a Lexus replacement but surprising good (except for one thing - relative to this thread) with only a 3 banger 1500cc turbo petrol with front wheel drive 6 speed auto. Clever thing is that the hybrid set-up drives the rear wheels so it is effectively (and when you need it) 4 wheel drive. This is really quite good in the weather we are having and is great fun 'launching' on roundabouts. Far quicker 'off the line' that the Lexus (which in itself isn't slow) Where it looses out is at higher motorway speeds - whereas the Lexus 'kicked-down' had a surprising turn of speed at 70 mph plus - this car trades this for 0-60's, which is fine for the town driving I mainly do. The one area which is most disappointing is fuel consumption - the best I've seen on a motorway run is 41 mpg - with an equally poor average of 31 mpg in mixed urban/city/M25. Considering it has a 1000 cc smaller engine than the Lexus (which in itself it a large engine) it makes one realise actually how good the Lexus is.

[Thackeray]

Over the last few months during the summer weather, my dashboard display showed an average of 50 mpg. The real mpg calculated from petrol bought and miles covered was just over 45 mpg. I'm quite happy with that as it's just above the average for the IS300h of around 44 mpg on spritmonitor.de. (You have to sign in to change the display from litres/100km to mpg.)

But since I last filled up, my mpg display since refuelling has plummeted to around 33 mpg (so that's probably around a real 29 mpg). I was wondering why this had happened so looked into it a bit more. First of all, I've been only doing journeys of 4 miles, in stop-start traffic, at an average around 12 mph, in temperatures around freezing. No fast driving at all since refuelling.

So I thought I would look at the display that shows fuel consumption minute by minute - I hadn't really looked at it closely before. The interesting thing was that for around the first five minutes of driving the car was doing around 20 mpg. When it was really cold, it might have been for the first seven minutes. Then when the engine had warmed up, it suddenly switched to above 40 mpg and even 60 mpg for some of the minutes. And after less than 20 minutes the journey was over, giving an average for that time of around 33 mpg. I'm not unhappy with that as I can see where the problem lies - I'm driving the car when the engine is cold with headlights, air conditioning, wipers, rear screen demister and heating all turned on .

But I'd be interested to hear of other people's experience in cold weather. Is there someone whose typical journey takes them straight from a cold start onto a fast road? In those conditions, how long does it take for the engine to warm up? Is it quicker than the five minutes I'm seeing before the mpg gets back to a more normal range? How does the mpg compare in those first few minutes?