why do 2010 cars all look like the 2009 Red Bull

In fact the cars don’t look like the RB5, but simply one major cosmetic aspect of the car has been inspired by Adrian Newey’s design, the nose. Newey himself terms it a “V” nose, not to be confused with the Renault “V” keel. Modern F1 cars all use raised nosed to improve airflow in between the front wheels and hence towards the rear of the car. The better airflow you can get up front the better the airflow routed over the top of the diffuser, and hence create more downforce.
Since the early nineties and up until last year teams conformed to the FIA technical regulations, where by the foot well of the car had to be a minimum of width and height. This of course suggests a rectangular cross section, and teams followed the rules to the letter (see below - left). What Newey realised is that the rules demand these minimum measurements, but not relation to each other. Thus the edges of the rectangle can be raised up and the middle drooped, creating the so called “V“ shape(see below - right). This reduces the obstruction between the wheels as the lower edges of the nose are chamfered.

This shaping is only really visible when the nose cone is removed and the cross section of the front bulkhead is exposed (see below in highlighted yellow). When the car is in race condition, the giveaway of the “V” nose are the two humps on either side of the top of the nose. These have little effect on aerodynamics or the drivers visibility.

Aside from the “V” nose, the RB5 soon found itself unsuited to the rise of the double diffuser. Its low line sidepods, pull rod suspension, gearbox and rear crash structure, all actually hindered the cars being as good as it could be. These rear end design features are not likely to be copied by other teams 2010. It was testament to the cars initial advantage as the fastest ‘non double diffuser’ car, that it remained a leader on pace up until the end of the season.