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I was just wondering if having a convertible with its top down is any more or less aero dynamic than a car just like it that has a hard top.

Also, if one were to get a car with a sunroof or moon roof took the glass out and sealed it up somehow, could it be slightly lighter than the same car without a sun/moon roof?

 
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less aero and depends on what u seal the sunroof hole with, if it's material lighter

 
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I was thingking if like alum, titainum, fiberglass, or CF was used

 
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the convert would be less aerodynamic with the top down the air would get cought up in the interior of the car causing drag. Most convertibles aren't fast enough to notice. Maybe a tenth or 2 at a drag strip.

lots of drag racers put " cf plugs" in thier sunroof to reduce wieght, but the inner structure around the sunroof will keep you from makeing it lighter that a non sunroof car.

 
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A convertable is less aerodynamic than a coupe of the same model. Just think about the fluid flow over the car. The roof is a nice curve for airflow and its all smooth. With the top down, you've got nothing past the windshield, so the air flows over the windshield and piles into the passenger compartment. Thats why you'll see Ferrari and others put a huge rake on the windshield, raise the rear deck up and put in the tonneau covers.... its to get as much of that air over the windshield and onto the back deck as they can, because then it flows off the back of the car (and keeps the rear end down).
Plugging a sunroof hole is almost always lighter because the sunroof w/ motor and rack is about 80 lbs. Even a steel plate the same gauge as the roof sheeting wouldn't be anywhere close.

 
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so for the sunroof thing, would it be lighter or not than the same car w/o one? Im saying if you seal it off and take out all of the hardware/motors/glass etc

 
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even with the top up the bumpy and not-so-smooth shape of the soft top is less aerodynamic.

 
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The top is fabric which is not very friendly to wind. So it will have a higher drag than the painted metal, but that's getting kind of picky.

 
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The easiest thing would be to simply close your sun roof and take all the motors out an and cut the back half of the rack. taking it all out and sealling it would be far harder. Not the hardest thing to do, but not nearly as easy as simply closing it and removing the motor and back rack. may want to put some sicon in the sealling area too when you close it the final time

 
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also the fabric sags and creates low spots on the roof surface so between air getting slowed down by it being fabric and the fact the air gets slowed down in the little recesses I would say yes it makes a small difference worth bringing up. Not alot...but a little.

 
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what about hard top convertibles, like the lexus, or cars that have a detachable one?

 
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Well as for aerodynamics, they will as good as the hardtop non convertible car. But they will lack the structural rigidity that a permanent hard top has and are usually heavier, so performance is a tad lower. Not to mention cars like the Mustang GT are actually lowered in horse power so that people are less likely to flip the convertible version, that’s actually a legal move on Fords part, and no I’m not sure if that applies to the ’05 Mustangs.