If you work on your own car, why not dress like a Porsche technician. I found these shirts customized for Porsche on the web. Take a look:

<a href="http://www.workingclassclothes.com/porschepg.htm" target="_blank">http://www.workingclassclothes.com/porschepg.htm</a>

$22.50 seems like a fair enough price....

 

I noticed they will add the PORSCHE logo to jackets for $4.00 - and the jackets are inexpensive, too.

Cool