Hybrid driving technique

[OldTrout]

Yesterday I drove my 450h to Mumbles and back from Oxford. On the way there I went the scenic route* with many roadworks, some dual carriageway but no motorway. 147 miles and about 4 hours. 35 mpg.

On the way back after a slow rush-hour crawl out of Swansea I used the M4 and A34. I was on cruise for about 145 of the total 159 miles. Just under 3 hours. 35 mpg.

I thought one of the mpg figures would be higher so I don't think I have mastered the hybrid driving technique yet.

Zotto suggested on these forums a "pulse & glide technique, and trying to keep the charge of electric Battery at about 6 bars." I am sure he is right but I'm not sure I understand. Is this saying I should accelerate up to the desired speed, then lift off until down by say 5 mph, accelerate to speed again and repeat? How hard do I accelerate? I am not heavy footed and will brake gently if I can. I'm not sure I have any control over the Battery do I?

Advice please.

Thanks, John

* this scenic route included one new part of the A465 Head of the Valleys road where the position triangle on the satnav was on a completely featureless bit of map. i.e. no roads showing at all.

[steveledzep]

You were lucky you didn't encounter bows and arrows on that uncharted stretch of the A465 !

I have no experience of hybrids, but I'm contemplating retiring into a GS450h, so I find your results interesting.

Any road up, cannot fault 35mpg in such a luxurious and quick motor car.

[royoftherovers]

John,

In my experience of 2 1/2 years driving the 450h, I find that overall (brim to brim) 35mpg is the best I can get. The car is big, heavy, a 3.5 litre V6 and a superb place in which to be.

Yes, if you accelerate gently to your required speed, then back off so that the energy is flowing to your Battery, you will not use fuel in the very short term, but OVERALL, my experience of 35mpg satisfies me. 

Just enjoy the undoubted pleasure it can give.

 

Regards

 

John.

[stevet]

When you think that owners of petrol supercharged Range Rovers are reporting 10mpg and not much faster. It shows how good the RX is.

[OldTrout]

I am happy with 35 - significant improvement on my 1998 GS300. I am curious to know how to do better. The two journeys were quite different. A couple of times on the scenic route the power needle did pass 200kW for overtaking. It really is a wolf in beautiful sheeps clothing.

It is much easier to drive away smoothly than the GS which always struck me as a rather sharp throttle response.

I wonder what the comfort an noise level would be if it had the same diameter tyres on 16" wheels?

John

[Zotto]

P&G technique is for hypermilers, if you like to spare gasoline but not obsessed by low mpg, the way to drive a powerful and wonderful car like GS 450h is to reach cruise speed in a normal way, not too fast but also not so slowly, then leave for a moment the right foot and then pressing again just to keep speed; when you have to slow down try to avoid if you can braking, but if you need braking the most efficient way is to press  brake pedal so that  regenerative braking (energy recovered and stored in hybrid battery) works without needing to loose energy in heat and brake pads. How? Give a look to energy meter and you will notice the indicator moving counterclockwise down from 0 KW: you recover energy  till you don't arrive with indicator totally down; after that point traditional brakes work and you loose kinetic energy (wasting brake pads).

All this recovered energy will help you to have better mpg.

[OldTrout]

Thanks Zotto. That pretty well describes how I drive. I am not a hyper miler.

I have exceeded 40mpg but that was slightly cheating as I waited until the engine was warm before doing a reset. I did not do this on Wales trip and on both legs of the journey the first few miles were under 20mpg. (Oxford 0900hrs and Swansea at 1730hrs.) What I found curious is that the two legs gave the same mpg despite the very different conditions.

I have also noticed that using the M40 between Oxford and Warwick it does not really matter if the cruise is set to 60 or 75, the mpg comes out the same.

The letter "Hybrid traction Battery conditioning review" posted today by jonathanhaguey is very interesting. It does suggest that as the Battery gets older its ability to  grab and hold the harvested energy gets poorer.

 

John

[Zotto]

The real difference worsening mileage is when you exceed 75 mpg.  The first miles are always the worst for consumption, because engine has to get hot and it needs more gasoline.

[Mike Hartland]

John said, above, "it does not really matter if the cruise is set to 60 or 75, the mpg comes out the same."

I have found the same. On a regular trip from Gloucester to Kent in my '06 GS300, I would get 36mph cruising at 70mph and almost 40mph cruising at 60mph.

I now find on the same journey that I get 40mpg whether I set the cruise to 60 or 70 mph in the GS450H.

[royoftherovers]

Mike,

Are your figures from the on-board computer or your calculations from brim to brim ?

My computer often tells me 40, whereas the brim to brim figure comes out at 35.

 

Regards

 

John

[Northern_Si]

I'm guessing the improvements made to the newer GS450h are quite huge. I'm current averaging 43 MPG according to the trip computer (so about 39mpg). Going from Bolton to Blackpool daily I'm getting an indicated 45 to 48MPG. This drops to 40 to 44 MPG coming home (I guess it is up hill!!). Going down to London and back I got 44MPG indicated. Over Christmas I drove to Spain and back and including quite a lot of 90mph on the toll roads I managed an overall average of 40MPG indicated. I'm well happy with this and is within 10% of what I was managing in my previous MB e350cdi. 

[crow1342]

hi, I have tried all styles of driving and average 28-29 mpg around town and 33-35 mpg on a run which I think is very good for a heavy powerful car,

[Zotto]

New version after 2012 of 450h improved mpg of 15%, impressive.