Aluminum and carbon fiber supercars will break themselves in half because of fatigue?

[Big time]

Aluminum and carbon fiber just don't have a fatigue limit.
[ame="http://en.wikipedia.org/wiki/Fatigue_limit"]Fatigue limit - Wikipedia, the free encyclopedia[/ame]
Repeated forces literally fatigue the material up to a point where a small force (even a bump) can completely break the material.

There was an F1 car racing in an historic racing event when the car broke in half leaving Frederick Kroymans legs exposed.
Ferrari F1 Car Destroyed by Putz in Turn 6 at Laguna Seca (Great Pictures!) - Team Juicy Racing's Skip Barber Racing School and Race Series Forums

Thus aging supercars with aluminum and carbon fiber supercars will almost have and expiration date no matter how well maintained?

[Matra et Alpine]

IN part true, but what the graph doesn't take in to account in that wiki article is that steel RUSTS and welds create stress points which focus the forces and thus simple graphs on wiki again prove themselves pointless ( as often the case with wiki )

You will see CRACKS long before you get to the point where a "small bump" can cause a break. So yes, owners need to inspect their cars ... jstu as those steel-built ones have to for rust too

We had a rear wing failure on single seater at speed on straight - luckily only a spin ended the "adventure". Looking at where the support beam failed it was clear there was a crack that was VERY OLD as it was showing corrosion in the crack for 10mm of it's length !!

[culver]

You can design such that the fatigue limit is out of practical consideration. Look no further than the DC-3 for an example.

At the same time when it comes to amateur race cars this is one of the concerns with carbon and in the old days aluminum monocoques. The aluminum monocoques often needed to be rebuilt after 8 years or so. The tube frames are often seen as less sophisticated but are relatively easy to repair and when designed right can last a long time. This is important in amateur racing where the cars are often driven for decades and long after they are no longer front line competitive.