Luxury, to me is needless levels of design and artistry made with care and attention directly by skilled craftsmen specifically to individual tastes.
If you think the industrialised use of wood, leather and metallic accents on mass production car is luxury, then I think you lack imagination.
Also, as a crude example...
The black pen, is plastic bodied. The BMW Car Club biro is metal bodied. The pencil is wood...
One of them carried a luxury price tag, one was free, and the other was about 20 pence. Guess which one's which?
The application of common materials that can be formed on a production line doesn't intrinsically define luxury to me, personally. I'm not saying using those materials is bad - it's simply one of things - I'm curious as to why people hold the belief that certain choices (which in reality are relatively limited to streamline manufacturing processes) imply luxury. I've supplied the industry on and off all my working life (just found out we're making interior bits for the new Jag), so the gap between real value and perceived value has always been a pet peeve of mine.