Trifle but impotant

Every material has it's own resonant frequency and an automobile has uncountable vibration sources in operating condition. As some strange noise was discerned from inside of dashboard on just in front of steering column, checked the original source where it comes. However carefully I might seek pealing out speaker cover and speaker, fuse cover and meter cover, I couldn't identify the origin of the clicking noise at all. Remembering the past experience over 30 years ago when I was keeping Skyline E211, same kind of noise came from bonnet hinge, I doubted the cause might be from the engine room, then finally found out the origin, plastic cover for checking body number that is required by Legal Inspection every two years. Just twisting by finger power giving some distortion to keep it tight in position could solve the chronic problem. It is often the case that any engineering plastic tiny parts shrink and distort after as long as over 10 years use, especially it happens in high temperature engine room. German made automobiles have tendency to get worse for plastic parts because of hotter motor combustion compared with Japanese one that might be brought by the difference of designing concept of motors, or that of plastic material quality?
Inconvenience found in NCP10 TOYOTA Vits, small but being suffered from I nervous hitting noise, that is strange hitting and clicking noise from drive shaft needle roller bearing comes up periodically, but wheel rotation or just changing the relations of wheel setting 180 degree eliminates the noise, how come? There must be some distortion on the wheel tracking or ill fitting between the wheel and tire positions? Anyway it is true that the noise is influenced by the external factor while actual use. The air filter for intake air of the motor has replaced as a periodical replacement parts.
I feel satisfied with the sophisticated TOYOTA's technology developing newer automobiles to have used a global strategic vehicle Vitz 1300 RS especially after the adjustment of axle constructive geometry and wheel alignment as exactly the same as the value mentioned in the maintenance manual. Not a little efforts were required to establish the alignment, because some loosening of sub-frame holding bolts for repositioning was obliged to correct the existing setback on frontal axle construction. Additionally, it's rear axle design based on torsion beam axle concept made it impossible to establish "Zero thrust", because the axle hinge bushes had many holes for enough compliance to support the anterior strong shock from the ground. Movable and deformable physical property here are very inconvenient for both correcting and establishing the precise axle alignment.
Though I started to learn and study about an automobile's constructions, the latter model NCP10 TOYOTA Vitz gives me tremendous information on the sophistication on the technology of the company again. From my standing point of view as one of a scientist, interpreting the intents of the designers and engineers of the production company is too interesting to stop to continue.
2 liquid type Clear Urethane coating procedure on the ugly bonnet of XH200 OPEL B-Vectra would be performed today, my skill in splay painting would be up this time?