Optimum speed to improve range on MG5 LR pre-facelift

[Another oldie]

Apologies if this is a silly question, but is there an optimum speed to aim to drive at to keep the battery as charged up as much as possible between chargers on a long journey on motorways/ A roads. I realise at 60mph you use less battery than 69mph but would driving at 50 ( if safe) help. I always drive in eco mode, but am unsure which kers setting to use.

 

[Verdigris]

ICE vehicles are optimised for economy at 56mph. Not sure if they use the same criterion for EVs but you will see many EVs shadowing trucks, which are limited to 56mph, on motorways.

However, as electric motors produce full torque at all revolutions, and wind resistances increases with the square of velocity, the slower you go, the more miles per kWh you'll get.

 

[Another oldie]

Thank you. That is useful to know.

 

[Verdigris]

FWIW I tend to drive at 40-50mph on ordinary roads and 56-60mph on motorways. I average over 4.5miles/kWh in summer and around 4miles/kWh in winter.

 

[Deep purple]

It's not quite true that the slower the better and driving slower than lorries on busy motorways is hair raising.
There is a base load from all the electrical stuff in the car (hydraulic pump, cooling pumps, heater/aircon etc) and the total KWHr these loads use from your available battery capacity over the length of a given journey reduces as the time to do the journey reduces.
As has been pointed out above the wind drag goes up with speed but it is a squared relationship not linear.
Best advice is that if you aren't in a hurry tuck in behind something large travelling at about 60 which will give a significant reduction in your drag and reduce the impact of base loads.

 

[Verdigris]

Yes, I should have added there is a law of diminishing returns in going slower. The rolling resistance and other "overheads" will tend to become a greater proportion of power use.

 

[emmrecs]

From other users on this forum I learned that for motorway and dual carriageway driving, 65 mph is the "recommended overall maximum". It's certainly what I try to keep to, with the occasional faster burst if I want to overtake a "slower" vehicle.

 

[kevin ellard]

From other users on this forum I learned that for motorway and dual carriageway driving, 65 mph is the "recommended overall maximum". It's certainly what I try to keep to, with the occasional faster burst if I want to overtake a "slower" vehicle.

I did a lot of that when I first got my facelift at the beginning of this year. I now don't bother unless I am marginal for range on a particular journey. Most of the time I have plenty of power to get home so I drive at whatever speed I feel comfortable. I also never bother with eco mode unless I am really struggling to get home on the current charge.

 

[Gomev]

Apologies if this is a silly question, but is there an optimum speed to aim to drive at to keep the battery as charged up as much as possible between chargers on a long journey on motorways/ A roads. I realise at 60mph you use less battery than 69mph but would driving at 50 ( if safe) help. I always drive in eco mode, but am unsure which kers setting to use.

Re Mode, whatever feels good for you. Same power just applied slower in ECO. Personally I prefer the normal feel of 'Normal'. Makes bugger all difference to economy in my experience.
Re KERS. Stop start traffic, slower roads, KERS 3, motorways, fast roads KERS 1. Reason for 1 is you lose more energy accelerating back up to speed than you gain slowing down too quickly on motorways.
Or if you are my missus just leave it all where it was when you got in the car (N2), she has never touched a mode/KERS switch since we've had it. Seems to make not a jot of difference around town.

 

[kevin ellard]

Re Mode, whatever feels good for you. Same power just applied slower in ECO. Personally I prefer the normal feel of 'Normal'. Makes bugger all difference to economy in my experience.
Re KERS. Stop start traffic, slower roads, KERS 3, motorways, fast roads KERS 1. Reason for 1 is you lose more energy accelerating back up to speed than you gain slowing down too quickly on motorways.
Or if you are my missus just leave it all where it was when you got in the car (N2), she has never touched a mode/KERS switch since we've had it. Seems to make not a jot of difference around town.

Kers doesn't make any difference on motorways either if you are happy to control your speed with the throttle pedal all the time or let the ACC do it for you. Always taking you foot all the way off the throttle whenever you are slowing down would be a waste of energy though.

 

[jackois]

I've never worried about range... all I need is 2 hours between stops.

Left Southampton fully charged, outside temp 8degC, arrived at Watford Gap northbound with 38%. Charged to 85% in the 30 minutes it took to drink a Costa, eat a sausage bun and get a pee. 20 minute stop at Woolley Edge to refill to 80% to give charge for running around Leeds.

General speed was 70, car fully loaded... I can't be doing with the faff of fuel saving...

 

[Tommy]

I find anything over 60mph eats up the battery if you are trying to maximise range. It is possible to get 5 miles/kWh in this car if you drive it like a granny - light foot on the go pedal - and keep well under the national speed limits, but it is not much fun.* Personally I find I get better economy when not using ACC, as it accelerates too quickly after a slowdown.

* unless you are a hypermiling geek (which I am ... sometimes )

 

[MG5 2022 driver]

All trucks are allowed 60mph on motorways so for safety (trucks not pulling out to overtake) I set the ACC to 65mph on my MG5 (post facelift). The wind is the biggest variable. I can sometimes only get 2.9 mi/kWh into wind but 5 mi/kWh going downwind.

i have a 7.5kWh unit (Zappi2) and charge from midnight to 5am at about 9p/kWh.

 

[NeFo]

"Best advice is that if you aren't in a hurry tuck in behind something large travelling at about 60 which will give a significant reduction in your drag and reduce the impact of base loads."

How far behind?
i have seen other cars so close i doubt they would be visible to the lorry's driver.
Is "visible in its mirrors" close enough?
How can you tell you are close enough?

 

[Verdigris]

How can you tell you are close enough?

You'll see it on the consumption meter. You can generally feel when you are in the "sweet spot".

 

[Deep purple]

If you use adaptive cruise control this should maintain a safe distance.

 

[MG5 2022 driver]

If you use adaptive cruise control this should maintain a safe distance.

I find that the ACC puts you so far behind the vehicle in front that there is little or no slipstreaming advantage.

 

[Deep purple]

Do you reduce the distance to minimum setting?

 

[Gomev]

I find that the ACC puts you so far behind the vehicle in front that there is little or no slipstreaming advantage.

Do you reduce the distance to minimum setting?

Also regardless of the setting the distance is relative to speed. i.e. distance to vehicle in front at 60 is further than distance to vehicle in front at 30 whichever setting you have it on.