Car

The interior of the car doesn't have to be very detalied and very precise because it will only appear vaguely in the transparency of the windows. The first thing is to create the bottom part of the car (it doesn't appear in the rendering but is important if we use a radiosity engine)

Next will build the chairs. I have started from 2 boxes that I edit mesh like this:

The little cushion that support the head is created from a torus with minimum settings , then edit mesh and we scale the vertexes that on the z axes, then mesh smooth.

The dash board is created from a network of spines:

Then we apply Surface:

The polygons we have to extrude are marked red in the image:

The polygons will be extruded several times:

We apply mesh smooth with 2 iterations:

The Driving wheel is created is build from a cylinder and a tube. Some faces of the tube is are extruded and them welded with the faces of the cylinder like that:

The gear changer : from a chamber box and a modified box:

On the chamber box we apply a noise then a mesh smooth. After that we edit mesh the object. Select the vertexes in the top-midlle position (soft selection is on), and we drag them down. We reduce the soft selection area, and pull up the vertex. Then we mesh smooth again.

The rear bench is created in a similar way as the front chairs:

Next comes a mesh smooth and a edit mesh. We select the faces from the down - center and we extrude them. Then we mesh smooth again.

The interior should look like this: