I definitely like the strong bold shiny metal look against the black fabric, perhaps with a dash of red or gold as well. I found having a wrench or spanner on the logo useful - helps to identify the company. Our uniforms are black, so something that will work well against that background. A font that is easy to read on the first glance.

Please note that 'Mobile Auto Repairs Sydney' is the complete name. 
We cannot use 'MARS' or 'MAR' - Sydney. We just need to have it full 'Mobile Auto Repairs Sydney'. 
 

The designs so far are smashing! Perhaps add a tool? Or if possible can the tool such as a spanner be attached to the 'Y' in Sydney? Just throwing out a little idea! 

Thanks