Am I crazy - long trip towing boat upcoming....

[Avendit]

@ 55mph, 100ft gives 11% improvement. the safe stopping distance at 50mph is 174ft.

You are only in trouble if the lorry can stop quicker than you, so that might be 10% that helps...

But you can get 39% fuel reduction at 10ft away from the truck

OK, I'm out. Just over half a car length away - that's serious range anxiety style driving.

I think your benefits would increase with speed, or allow you to back off. I wonder if the improvements would be better with an EV for the same reason we loose more % range with towing as @Cardo said?

 

[Mrklaw]

You are only in trouble if the lorry can stop quicker than you, so that might be 10% that helps...

OK, I'm out. Just over half a car length away - that's serious range anxiety style driving.

I think your benefits would increase with speed, or allow you to back off. I wonder if the improvements would be better with an EV for the same reason we loose more % range with towing as @Cardo said?

at that point you'd be better off deploying a rigid pole and hooking onto the back of the truck

 

[Adopado]

I wonder if the improvements would be better with an EV for the same reason we loose more % range with towing as @Cardo said?

I'm thinking that the benefit may be less for a Tesla because it has already been optimised for aero whereas a less aerodynamic vehicle has more to gain by travelling in an aero protected bubble. [As a thought experiment, taking this idea to the extreme, if it were possible to have a "perfectly aerodynamic" vehicle there would be no gain whatsoever from travelling behind some aero protection. On the other hand a brick shaped vehicle would have lots to gain.]

 

[init6]

You are only in trouble if the lorry can stop quicker than you, so that might be 10% that helps...

They do have a habit of stopping very quickly:

Or not stopping:

 

[Avendit]

Or not stopping:

That second one shows a stunning amount of exceptional driving from everyone to be fair! The lorry driver shepherding the runnaway trailer and the white car beside it escaping. Probably better than I would do.

 

[init6]

That second one shows a stunning amount of exceptional driving from everyone to be fair! The lorry driver shepherding the runnaway trailer and the white car beside it escaping. Probably better than I would do.

There go the white seats

 

[Peter 224]

The first one looks as if it was a horse box... criminal lack of care by the HGV driver.

 

[init6]

The first one looks as if it was a horse box... criminal lack of care by the HGV driver.

Literally:

A27 crash: Lorry driver caught on camera texting before collision

Derek Holland texted and used both hands to peel a banana before a crash which injured three people.

www.bbc.co.uk

 

[MrBadger]

I did think a sticky or wiki with w/mile experiences with different configurations would be handy for people. Towing, bikes, roof boxes etc.

But we have lots of stickies already, and this would take a bit of effort to ensure reasonably consistent records. Do you use the car's rating (I never look) or abrp's weighted 65mph number (not everyone will have). Up to @VanillaAir_UK really?

I am no longer a moderator. In addition to the previous global incumbents @drewpost and @GeorgeSymonds are the local UK and Ireland sub forum moderators now.

 

[Peter 224]

Literally:

A27 crash: Lorry driver caught on camera texting before collision

Derek Holland texted and used both hands to peel a banana before a crash which injured three people.

www.bbc.co.uk

Not sure which is worse, but at least the prisoner can be treated.
Horses injured in van accidents tend to be put down.

 

[init6]

Not sure which is worse, but at least the prisoner can be treated.
Horses injured in van accidents tend to be put down.

Sorry, I meant literally 'criminal lack of care'

 

[Cardo]

I’ve been giving some thought to over-run brakes. I can see how with an ICE vehicle over-run brakes make sense, allowing the trailer to brake itself when the towing vehicle is slowing down, reducing strain on the towing vehicle’s brakes (and fishtailing, etc.). However, with an EV, especially a relatively heavy and poised EV such as a M3, the trailer auto-braking each time the car regens will hinder the effectiveness of the regen, and possibly cause increased drag on the tow vehicle.

I appreciate there’s already been some discussion about adjusting the trailer brakes, however I’d like to pick the brains of those who know about trailers and their over-run braking systems. We’ll be collecting our trailer tent in a couple of months. It’s a fairly hefty unit and we’ll likely be maxing out the car’s 1000kg towing limit. In an attempt to optimise range, I’m wondering whether it would be possible to have the over-run brakes adjusted so they require a harder braking force to engage, and thus avoid unnecessary auto-braking and reduced regen? Would this be a fairly simple process of an adjustment, or are the systems set in the factory to actuate at a specific force with little/no adjustment available?

 

[heckler1]

I’ve been giving some thought to over-run brakes. I can see how with an ICE vehicle over-run brakes make sense, allowing the trailer to brake itself when the towing vehicle is slowing down, reducing strain on the towing vehicle’s brakes (and fishtailing, etc.). However, with an EV, especially a relatively heavy and poised EV such as a M3, the trailer auto-braking each time the car regens will hinder the effectiveness of the regen, and possibly cause increased drag on the tow vehicle.

I appreciate there’s already been some discussion about adjusting the trailer brakes, however I’d like to pick the brains of those who know about trailers and their over-run braking systems. We’ll be collecting our trailer tent in a couple of months. It’s a fairly hefty unit and we’ll likely be maxing out the car’s 1000kg towing limit. In an attempt to optimise range, I’m wondering whether it would be possible to have the over-run brakes adjusted so they require a harder braking force to engage, and thus avoid unnecessary auto-braking and reduced regen? Would this be a fairly simple process of an adjustment, or are the systems set in the factory to actuate at a specific force with little/no adjustment available?

I'm not an expert on trailers by any means, however my understanding is that a braked trailer should have the ability to isolate the braking function. Most work on a spring which the weight of the trailer pushes when the tow vehicle slows and activates the brake on the trailer.
By isolating the spring, or locking it out I suppose, it would enable the trailer to be reversed without the brake activating.
All the above may be bunkum and I am open to being castigated by someone more knowledgable than me...

 

[fyonn]

A more aerodynamic trailer would make a huge difference

Is there such a thing as an aerodynamic trailer? all small to medium ones that look like they'd fit behind a saloon car (as opposed to a landie, transit or truck) I've seen tend to look like cheap steel boxes on wheels..

I've got an M3LR coming mid Feb and I ordered it with a towbar, mostly to use with a bike rack but I figured I'm coming from a discovery 4 with ample boot space so maybe the option of a trailer at some point would be useful.. but obviously if I was going to get one, I'd rather get a nice aero one if such things a) exist and b) aren't stupidly expensive...

 

[p3k4y]

This post is fascinating, especially the aerodynamic aspect. I found this regarding towing with a Model X

It basically compares the available ranges when towing 2 vehicles with completely different aerodynamic profiles. It makes me wonder whether something such as this Aeroplus | Roof-Mounted Wind Deflector | Caravan Accessories | Purple Line | Australia would make any big difference?

 

[Wol747]

It tends to be forgotten - or rather, ignored - that the aerodynamic effect on drag is absolutely identical for ICE cars. It's just that with them you can put a jerrycan in the back which compensates, if you need the range for a particular sector.

 

[Avendit]

I think it's to do with the baseline of the engine being on. You are already running the engine and throwing lots of power out of the exhaust, so a 50% increase in drag (or losses for temp, or weight or what ever) only makes a barely noticeable 10% difference to the consumption.

Increase the drag of of an EV by 50% tho, and because there are so few other losses, you see your consumption increase by pretty much 50%.

The change to the ICE is masked by all the other inefficientcies.

 

[Wol747]

I think it's to do with the baseline of the engine being on. You are already running the engine and throwing lots of power out of the exhaust, so a 50% increase in drag (or losses for temp, or weight or what ever) only makes a barely noticeable 10% difference to the consumption.

Increase the drag of of an EV by 50% tho, and because there are so few other losses, you see your consumption increase by pretty much 50%.

The change to the ICE is masked by all the other inefficientcies.

No dispute there - I was just remarking on the drag actually being identical. (Which is obvious!)

 

[Jason71]

No dispute there - I was just remarking on the drag actually being identical. (Which is obvious!)

It is obvious. As are the reasons we ignore it on ICE. The effect on range is very different. As Avendit said. Drag that causes 50% range loss on an EV might be only 10% on an ICE car due to its inherent inefficiency. Which would hardly warrent a Jerry can. Especially sInce range is less critical there to begin and there are lots of petrol stations.
If the real world effect was as minimal on EVs we would ignore it as well.

 

[Wol747]

It is obvious. As are the reasons we ignore it on ICE. The effect on range is very different. As Avendit said. Drag that causes 50% range loss on an EV might be only 10% on an ICE car due to its inherent inefficiency. Which would hardly warrent a Jerry can. Especially sInce range is less critical there to begin and there are lots of petrol stations.
If the real world effect was as minimal on EVs we would ignore it as well.

I'm not at all sure I follow the reasoning here. A loss of efficiency is a loss of efficiency, and it's over and above the inefficiency of the ICE, I would have thought.