Tiago

The sedan has 0,28 of Cx and the touring 0,30. This is the numbers given by BMW but what about the M exterior package? Will it have the same Cx? How much will improve the Cx by lowering the car, about 35mm (eibach)?

ImolaRedM

I'm not sure if Cd (Cx) data is available with the aero kit.

Heiss5

The difference is going to be minimal at most, and unless you plan on significantly surpassing speeds of 155mph the slight difference isn't going to matter at all.

JMB

I haven't seen the Cx for the M pack, but I bet that Cx will be worst than with the standard pack. Aero packs are normally designed to provide more downforce, and you can only increase downforce if drag is higher, ie. Cx increases.

For a E60, a 0.01 increase or decrease in Cx means aprox. 3 Km/h difference at very high speeds (200Km/h).

hythe

Bizarrely, with the Alpina aerokit on both, the factory guys were able to run the B5 Touring to a higher top speed at Nardo than the B5 saloon... If you want to reduce Cd vs the SE, the Alpina kit will be more effective than the M-Sport kit, I'd expect - the Alpina kit was specifically developed for a 200mph-capable car, after all.

I believe the B5 sedan has a Cd of 0.29, but bear in mind it has 245/275 tyres and a bigger diff hanging in the underbody air.

Tiago

At 180mph the difference of 0.02Cx means 25hp and 7km/h About drag vs downforce, correct me if i'm wrong but, if you lowered a car you will improve the downforce (you will have less air flow under the car, this will reduce the lift and it will improve the downforce), but you will improve the drag too (lower drag and higher downforce), or not?
As for the alpina B5 sedan with a Cx of 0.29, the original sedan has a better Cx (0.28). I bet that Alpina may have a much better downforce with only 0.01Cx of sacrifice.

hythe

Quite possibly true - but also the SE figure of 0.28 wasn't measured while the car was wearing Alpina-sized tyres...

The more interesting figure across a broad range of cars is CdA, anyway, rather than purely Cd/Cx - the resistance is a multiple of the frontal area (A) and the drag coefficient (Cd)

Heiss5

I think the bottom line here, is that unless Tiago is trying to break some land speed records in an E60, he probably should worry about how much the drag is going to change on his car. He's really only going to be gaining 2-5mph if he's lucky or losing 2-5mph if his unlucky, and I don't know about you guys, but I still haven't even attempted to hit top speed in my car yet.

hythe

Really? No fun...

I've hit an indicated 175mph before I ran out of (clear) road - car was still pulling like a proverbial train.

Heiss5

Yes but you have the Alpina B5, your car can actually go that fast. I've hit slightly upward of 100 a couple times, but I've never really gone for it. I don't know why not, just waiting for my Bugatti I guess...