zatoman

Saw a C&D article on automobile center of gravity. Got me to thinking about a few things regarding the Q5, so I will throw out a few questions and see if anyone has an answer.

1. Does anyone know how much weight the panoramic moon roof adds to the Q5?
2. Since the moon roof weight is, ah, on the roof, how much would that effect the vehicles vertical center of gravity?
3. Would a Q5 without a moon roof score noticeably better in the road tests run by Consumer Reports? (They don't rate the Q5 particularly well WITH the moon roof)

Thanks for any input.

zatoman

Just read an article that said BMW added an optional carbon fiber roof to lower roof weight and lower center of gravity.

Chawski

I'm willing to bet the roof and the electronics weight at least 200#. Yes, it is somewhat of a big deal having that much weight up top, however it's a suv, not a track car. The roof won't be the difference between it flipping or not.

If the car weighed 2000#, yes having that much weight up top is noticed, however with the weight of the rest of the car you'd never notice the difference compared to a sunroof delete version

The CF roof on the bmw is an interesting option. Cars have kinda hit a plateau on reasonably priced advancement so it's all down to weight and aero to improve performance and efficiency. Something I'm interested in seeing is when the USA allows side view cameras instead of mirrors.ive seen estimates for 1.5 to 2 mpg improvement in simply the drag reduction from the mirrors

patmurphey

I'll bet the dummy brake cooling scoops cause more drag.

Chawski

Would really be cool if someone could test that. I sense you're probably saying it somewhat jokingly, but they really are crap for drag. If they actually work, that would make a higher pressure zone in the wheelwell. I'd love to see active shutters on the main grille and the brake ducts. Lots of cars are going that way and they really do make a difference.

For high performance driving, you need that radiator surface area, however with cruise control and especially in the winter, you can get by with much less grille opening.

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MAMOHT

AndroidRobot

BMW has shutters on the front grill (my car has them) and I believe they do make a difference. While there are more factors to consider the X3 does getting better mileage on both trims than the Q5 in it's trims (i.e. the SQ5 too).

A CF roof only makes sense on sedans or ultra high performance (expensive) vehicles i.e. the RS5,6,7,R8, M3,4,5,8 etc. I think dropping the car 1" whether via an air suspension or sport springs will help more than removing a sunroof on an SUV.

Chawski

The CF roof actually makes much more sense than just marketing jargon. Dropping weight is vital, especially with mpg across the fleet. Anything you can do to decrease weight is a great thing for any car, be it a sports car or a semi truck. With the cost of CF coming down, it makes much more sense. Much cheaper for BMW since they recently invested tons of money in CF fabrication.

Despite a lot that I've said against it, carbon ceramic brakes are also great, just cost prohibitive. When they get down to maybe 2 to 3x the cost of steel brakes, you'll see them on everything.