ELI5 exactly why our cars are not supposed to tow

[codys21]

First, I'm not immediately interested in towing anything (though I do plan on installing a hitch for a bike rack), but it would be nice to have the option to tow a small utility trailer or something of that nature. I also understand it's not necessarily what a vehicle can tow but more about what it should tow. And I know renting or borrowing a tow vehicle is always an option.

I know towing involves more than just the torque figure of the tow vehicle, but our cars certainly have enough hp and torque. Plus, we have great brakes, the engine's cooling system is top notch, and even with the DCT, we can stick the car in whatever gear we want and it'll hold it there. Suspension is pretty stiff so a bit of tongue weight won't drop the rear end too much. Plus, I have the F83 so the frame is stiffened further.

I also know the US is more strict is certifying tow ratings (or is it the manufacturer who lowers it themselves for the US?). For example, a Camry has like a 1,000lb tow capacity in the US but apparently 1,200-1,600kg braked capacity in Australia (per Cars Guide). Similarly, the 4 series is not rated to tow in the US but has a ~750kg unbraked and ~1,800kg braked tow rating in the UK and Australia. The M4 is not rated to tow anywhere.

We've towed a small enclosed uhaul trailer a couple times with our Ford Fusion (that actually has a tow rating of 2,000 lbs) on a flat freeway doing about 70mph. No obvious issues, other than mpg. It just seems to weird to me that a Fusion or Camry or base 4 series can tow, but not an M4.

Again, this is all pretty hypothetical, but I'd just like to get some input on the actual reasoning instead of just "don't do it" or "rent a vehicle".

Thanks!

[SYT_Shadow]

On gts1 we have a stealthhitch and tow a small trailer with 12 tires.

Of course you can have a bike rack etc, zero reason not to

[NSX2M4]

Here is the thing though.
I have a dual jet ski trailer and two super light weight skis. Total skis with the trailer weights about 1200 pounds. I tow them with an old 2010 Acura MDX with AWD and the car starts to cry uncle after 50 miles of towing or so. The brakes start to fade really bad.
So, technically you can tow with this car but at the cost of replacement parts, I wouldn't recommend it.

[codys21]

Originally Posted by NSX2M4

Here is the thing though.
I have a dual jet ski trailer and two super light weight skis. Total skis with the trailer weights about 1200 pounds. I tow them with an old 2010 Acura MDX with AWD and the car starts to cry uncle after 50 miles of towing or so. The brakes start to fade really bad.
So, technically you can tow with this car but at the cost of replacement parts, I wouldn't recommend it.

Just Googled it and apparently that vehicle has a 5,000 lb towing capacity. Ouch.

But our cars again have more power, torque, and considerably better brakes. So it sounds like our cars would have less trouble towing your jet skis.

[M3SQRD]

Originally Posted by codys21

Just Googled it and apparently that vehicle has a 5,000 lb towing capacity. Ouch.

But our cars again have more power, torque, and considerably better brakes. So it sounds like our cars would have less trouble towing your jet skis.

A big part of it has to do with packaging and design requirements/objectives. For a performance sports coupe/sedan towing is likely not even on the list. You need to have structure capable of supporting the load, especially under braking, and transferring the load into the chassis. You could design the f8x to have a decent towing capacity but it would directly impact the exhaust layout (potentially lose dual centrally located exhaust tips based on BMW’s preferred one large central muffler), trunk subfloor, subframe geometry, bumper design/airflow, easy open trunk (don’t mess with peoples’ comfort features!), etc. It would be a feature if there was high enough demand for towing with a M3/4. Considering tow packages are an afterthought on X series vehicles, you’re not going to find it on a M series vehicle.

[NSX2M4]

Originally Posted by codys21

Just Googled it and apparently that vehicle has a 5,000 lb towing capacity. Ouch.

But our cars again have more power, torque, and considerably better brakes. So it sounds like our cars would have less trouble towing your jet skis.

It's not so much the trouble I mention as much as the, "wear".
Be prepared for brake fade, rotors warping, etc. All of which my MDX started to have after buying some water toys.
You, "can" tow sure. But, it's a different world especially when you factor in drag.

[SYT_Shadow]

Even the normal M3 has brakes that can put up with some track abuse, same as the transmission and engine cooling. A small trailer will do absolutely nothing negative to the car.

[M3SQRD]

Originally Posted by SYT_Shadow

Even the normal M3 has brakes that can put up with some track abuse, same as the transmission and engine cooling. A small trailer will do absolutely nothing negative to the car.

What does your hitch connect to? Do you have a picture? Just curious to see how you integrated it. Twelve track tires+wheels are easily pulled by the GTS

[SYT_Shadow]

Originally Posted by M3SQRD

What does your hitch connect to? Do you have a picture? Just curious to see how you integrated it. Twelve track tires+wheels are easily pulled by the GTS

The hard points the rear bumper beam connects to. I'll have to send pic over!

[FXMR]

Snapped this a while back. These things can tow with ease

Yes, that enclosed trailer was actually being towed by the F80.

[codys21]

Originally Posted by SYT_Shadow

The hard points the rear bumper beam connects to. I'll have to send pic over!

What hitch did you get? I know some here have the hidden hitch, though apparently it's no longer offered strictly in F8x fashion. Now it's only for F3x but apparently that fits just the same?

[codys21]

Originally Posted by FXMR

Snapped this a while back. These things can tow with ease

Yes, that enclosed trailer was actually being towed by the F80.

Wowza, that's probably a bit more than most here are looking for lol

[SYT_Shadow]

Originally Posted by codys21

What hitch did you get? I know some here have the hidden hitch, though apparently it's no longer offered strictly in F8x fashion. Now it's only for F3x but apparently that fits just the same?

We got the hidden hitch for the F80 although we have an F82. It was easy to make it fit.

[codys21]

Originally Posted by SYT_Shadow

We got the hidden hitch for the F80 although we have an F82. It was easy to make it fit.

Ok you must've bought it a while ago. Right now, no F8x options are available, but F3x are.

[SYT_Shadow]

Originally Posted by codys21

Ok you must've bought it a while ago. Right now, no F8x options are available, but F3x are.

I'm sure the f3x one can be made to fit as well!