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      12-06-2013, 05:41 PM   #1
paradoxical3
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The X1 is more aerodynamic than it looks

Over on N54tech, I was discussing trap speeds for drag racing in a thread. I mentioned how my X1 was at 12.1 @ 111.2mph where one of the BMS cars was at 12.2 @ 115mph, which is due to the better traction of the AWD. The BMS car has significantly more power according to the trap speed, but I still win in the ET because I get a better launch.

Terry made a comment that the X1 being a brick was probably killing me at higher speeds. At first I agreed, but then I did some research:

BMW X1 drag coefficient: .32
BMW X1 frontal area: 2.34 sq.m

BMW 335i drag coefficient: .30
BMW 335i frontal area: 2.17 sq.m

In other words, the BMW 335i only has 1.8 square feet less frontal area than the X1. Keep in mind this may change for the M-Sport versions, I could not find published specs for the M-Sport kits.

With that info, we can compute lost horsepower at a particular mph.

At 100mph, the X1 has a power loss of 53.7 horsepower. The 335 would have a power loss of 46.7 horsepower.

The upshot? The X1 is aerodynamic enough where the difference between it and the 335i at 100mph is only 7 horsepower. Less than an intake. The faster you go the worse it gets, but even at 130mph it's about a 16hp difference.

Okay, that's impressive. But the 335i is a tremendously well designed car from an aerodynamic standpoint. Let's stack the X1 up against some American muscle - the 2012 Boss 302 Mustang:

BMW X1 drag coefficient: .32
BMW X1 frontal area: 2.34 sq.m

Boss 302 drag coefficient: .36
Boss 302 frontal area: 2.248

HP loss @ 100mph for the X1: 53.7
HP loss @ 100mph for the Boss: 58.1

The X1 actually GAINS horsepower on the Boss the higher the speed. This may be one reason why the X1 is punching so far above it's weight at the drag strip and in roll races. Power is just one component of speed.

Not too bad for a suv.

Last edited by paradoxical3; 12-06-2013 at 05:54 PM..
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      12-06-2013, 06:39 PM   #2
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Excellent statistical analysis, paradoxical!

I had no idea; I too thought the X1 had the aerodynamics of a brick.

Love how versatile the X1 is.
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      12-06-2013, 07:45 PM   #3
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Wow. Cool numbers. That explains a lot actually. That and the HP to WT ratios.
I was wondering why the X1 does so well
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      12-18-2013, 08:58 PM   #4
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I bet too, with your car being slammed that your Cd will actually be more inline with a 3 series. Possibly even better.
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      12-19-2013, 08:14 AM   #5
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But there is still too much wind underneath the car at high speeds, making it less stable. It is pretty uncomfortable and sometimes scary driving at 200 km/h at the Autobahn, especially when there's headwind
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      12-21-2013, 04:26 AM   #6
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It also explains the excellent fuel economy I recently got on a 450mile round trip. 48.2mpg going south and 52.3 coming back North
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      12-21-2013, 06:11 AM   #7
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Quote:
Originally Posted by Naambezet View Post
But there is still too much wind underneath the car at high speeds, making it less stable. It is pretty uncomfortable and sometimes scary driving at 200 km/h at the Autobahn, especially when there's headwind
I think this must be a difference between your version of the X1 and the new US version. Perhaps it's the M-sport suspension, but I was doing 140mph (225kph) on the track and it was extremely solid and composed - not scary at all.
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      12-24-2013, 09:58 PM   #8
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triple digits no problem at all, move over farm truck bam -
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      01-03-2014, 12:49 PM   #9
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Great info.
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      01-03-2014, 01:18 PM   #10
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Well, can someone tell me why other cars with the same engine can get higher top speeds than the X1? Even the 5 series has an higher top speed rating than the X1, which weighs 200 kg more.
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      01-03-2014, 02:53 PM   #11
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Is top speed data empirical, or is top speed dictated by tire ratings or otherwise electronically limited?
It may be the lads at BMW thought it a bad thing for the smallest class to have a higher top speed than some of its pricier brethren...
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      01-03-2014, 07:20 PM   #12
paradoxical3
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Quote:
Originally Posted by Naambezet View Post
Well, can someone tell me why other cars with the same engine can get higher top speeds than the X1? Even the 5 series has an higher top speed rating than the X1, which weighs 200 kg more.
It's electronically limited.

I have the M-Sport package and with that, BMW raises the top speed to 155mph. I don't know if that is available overseas.
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      01-04-2014, 06:02 AM   #13
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Quote:
Originally Posted by paradoxical3 View Post
It's electronically limited.

I have the M-Sport package and with that, BMW raises the top speed to 155mph. I don't know if that is available overseas.
It isn't. They only limit it at 250 km/h. With my X1 I can go over the stated top speed(220) when I have the wind from behind. And the differences are not that huge with the same engine
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      01-04-2014, 10:17 PM   #14
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Some quiet night, I'll have to see what mine will do out on the interstate.....
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