How much faster can Cars go round a track?

I was thinking about F1 today, and thought are the lap times these cars posting the fastest you can safely go round a track?

Do you think there is any room for improvements with materials and engines to allow a few more seconds per lap?

I personally do think that there is room for a faster time, Give the car more movable surfaces (such as front wing adjustments, intake ducts and even the horizontal fins, to allow better cornering) The engines can get turbos back, and the tires made a bit wider, to allow more grip. The body work can be made lighter using carbon nanotubes even?

Are these reasonable suggestions or have we reached the theoretical limit on how fas a vehicle can go round a race track?