When you say that Formula 1 cars have better aerodynamics than a production car i think that you are over simplifying things a little. I agree that F1 cars have great aerodynamics however theres a little more to it then just good and bad. An F1 car has a huge amount of down force compared to a production car. This is the great part. However i believe that an F1 car also has significantly more drag, which is particularly bad for the top speed of the car. Things like wings, fins, and the like help with down force and other aspects of aerodynamics but in most cases increase drag. Therefore there is always a large trade off between drag and down force. This is one of the things they are talking about when they mention the "balance" of the car. Although that also refers heavily to the balance of understeer to oversteer. Anyway drag is what slows the cars down on the straights so they try to minimize it. But downforce is what makes an F1 car so fast in the corners so they try to maximise that. This means that at most tracks it is quicker for the cars to go slower on the straights but faster in the corners. A great example of this is the force india cars. Their cars tended to have less down force and also less drag. This meant that their balance of down force to drag was poor at most tracks so their lap times were usually pretty slow even though they often had the fastest speed trap speeds. Also at the tracks where less down force was needed the force india cars became very competitive. Getting back to the original point production cars are designed to have far less down force than an F1 car and also generally have less drag.

Another thing to consider is that the power to weight ratio only has a significant affect when the car is accelerating. When the cars approach their terminal velocity generally their rate of acceleration is very low so mass has much less affect. In fact the equation used to calculate the power required to overcome drag does not include the mass since it assumes that the velocity is constant. Therefore the drag coefficient and power of the car are by far the most significant factors that limit the top speed.

Here's a link to some more information about drag.
http://en.wikipedia.org/wiki/Drag_(physics)

Hope this helps. Feel free to correct me or to ask for clarification.

^^^ I would simply re-iterate that no matter how clean an F1 car is trimmed out, drag increases exponentially with speed.

Take a given speed (V), and its attendant drag (D); double the speed (Vx2)and the attendant drag is DxD, NOT Dx2.........

AT Bonneville, they took the Honda F1 car and ran it, achieving 220

http://www.motocrossactionmag.com/ME2/dirmod.asp?

sid=&nm;=&type=news&mod=News&mid=9A02E3B96F2A415ABC72CB5F516B4C10&tier=3&nid=8CC5785F512A4E52A9C11BE9035C0A91

A couple of things that prevent higher top speeds, 1) Open wheel vs closed body (think LMP car) the aero drag on an open wheel car.
2) The bodywork, floor and wings are all designed towards downforce. Unlike the sister IRL cars which are designed for maintaining faster speeds with less downforce and achieve higher top speeds at Indy. In 1996, the Indy cars pulled 240 mph on the straights.

http://www.youtube.com/watch?v=W82DsPkgV-U

ua... try 413.2 kph or 256 mph

All I can hear is Jeremy Clarkson screaming "POWWWAAAA!!!!"