I’m not seeing where I can customize the client details, what I’m wanting to do is have year make model on one line (like the address) is this possible
This is certainly possible, but you’ll need to dig in and customize the invoice design for this.
https://invoiceninja.github.io/docs/custom-fields/#snippets
Go to Settings > Invoice Design > Customize
And create a new design selecting the template which you wish to extend.
Then you’ll want to go into the Body Tab and find the selector which may look like this
<div id="client-details"></div>
Our system automatically looks for this section and injects the systems precompiled client details, but you’ll want to remove/rename client-details into something else… like client-details-custom
Now within that section you can format your data as you wish. The link I have included at the top should flesh out most of this and also include all of the variables you can use to customize your design.