The two images below show an interesting comparison between the component parts of a car in the 1940's and a modern car.
The VW Beetle pictured above is made up of just under 5000 parts, whereas a modern car, according to Toyota, will have in the region of 30,000 parts (this can of course vary quite a lot depending on make/model)
The most obvious change when comparing the pictures is the move away from a separate body and chassis to the one-piece monocoque construction we see now. The multitude of safety systems such as ABS, ESP, Airbags and even seat belts (which the Beetle didn't have originally) add to the parts count as do all the new emissions, comfort and entertainment systems we have on modern cars.
Cars are expensive bits of kit but when you think of all the parts that go into them you start to appreciate where some of that money goes. Imagine you averaged out the cost of every one of those 30,000 parts to €1.00 each, which is perhaps not as wildly unrealistic as it first sounds (yep, €1.00 is expensive for a nut or bolt but it's very very cheap for a tyre or a door!) Your average €30 grand Golf or whatever starts to look like reasonable value!