first, it is made of plastic, not metal.
second, this little unsightly thingie adds about 140 kgs of additional downforce to rear wheels at speeds above 100-120 mph, if i remember it correctly.
i think its about the personal priorities, but its not just a decoration, i can assure you of that.
I find it hard to believe that that little thingy can produce 300# downforce at any speed.
And that it is absolutely necessary. I believe the 540 can also hit a limited 155 and I don't recall any aerodynamically induced stability problems. And, with a .31 cd, which ok but not anything great by '00 standards, the air is probably pretty dirty already back there. I wonder if the spoiler is really high enough to escape the boundary layer.
It definitely is not a styling tour de force.
So...where did the 140kg number come from? [email protected] is still [email protected] And, can it be removed like the name badge, or due to drilled holes and painting dependencies is it a permanent fixture?
I am inclined to get it if either: it is easily removable; or it really adds some performance value.
I probably know more about light airplanes then about cars... And this little thingy spolier would need speeds of over 200MPH to effect lift, especially because it has airflow (pressure or vacume) on only one surface..
In any case, I rather have thecar look good, then argue about ounces of lift/drag at speeds I will rearly drive at... my $0.02..
Actually, I think the spoiler look pretty cool. It's subtle and restrained. I read an interview (don't remember where) with one of the design engineers for the M5; he said it produces around 300lb of downforce at 120mph or so. If it wasn't helpful, I doubt they would have included it. Then again, if it was necessary for safety, it wouldn't be an option.
this is not my estimate about the downforce but official figures, the only question is about the magnitude...but i am sure its in the excess of 100 kgs
its no cost option...you can delete it or have it without any additional cost
I attempted to have this deleted originally from my order in February '00. I was warned by BMW that the car could become unstable if I planned to drive at any high speeds. I decided to keep it. If I find a better looking one at a later date, maybe I'll change. For now it works.
DO NOT take off the spoiler, it adds about 30 hp @ 5500, 20 lb of torqe above 1250 rpm's, drops the cd to .25, and increases the top speed about 7 MPH. Almost as impressive as my Type R sticker, which gives me 50 extra horses. j/k
If you dont like it,, you can have it deleted from the options. beauty is in the eye of the beholder. I think it beholds beauty. It would be great not to have it if you were making a sleeper though (along with the badge deletion).
I owned a E39 540i (obviously without the spoiler) and now the M5.
I am not the kind of guy who take pleasue of washing his car on a perfect sunny day.
I do realise there seems to be more dirt collection on the top of the rear bumper on the M5 than the 540i.
Could it be the spoiler?
If that's true, at least the spoiler is good of collecting dirts onto your rear bumper
I find believe that it could possibly add 300# of down force ( read: lift acting towards the wheels 0r negative lift).
Lift = coefficient * density of the air *(velocity squared divided by 2 ) * wing area
The coefficient Cl is determined experimentally and may be considered a constant.
Yes the wing (spoiler ) area is small, however what the lift equation basically states is that as the speed of the car increases the downforce that the spoiler produces increases exponentially. So 300# downforce at 120 mph would be alot less than 150# downforce at 60 mph.
I am alot more used to dealing w/ highspeed aircraft and I can tell that even a small change in speed will result in a large change in the available lift.
I had a 540i 6 speed and have had it close
to top speed (140 mph), it was very stable!
Can't imagine bmw offering to delete it if
the car wouldn't be. I really think the car
looks better without it. I also think bmw
could have done a better looking job with it.
Downforce created by spoiler rises exponentially with speed and has NO significant aerodynamic effect with regard to stability below 100 MPH (160km/h). Change of airflow pattern created vy the spoiler will change where the dirt falls, but that shouldn't be a problem (a clean car is a clean car right?).
I would say YES - go for the spoiler because (1) you need it when you drive fast (2) it's subtle, which is what the M5 is all about (unlike some cars) and (3) it's a unique feature of the M5 which makes the package look complete.