Lower the opacity of the photo layer, and position it over the car in the template.
If the photo still doesn't fit, you can rotate it, or even change its perspective. This is an extreme example, to give you an idea.
Resizing, rotating, and such can degrade the image quality a little bit each time, so we'd normally be concerned about overdoing it. But we aren't concerned here, since we won't be using any part of the photo itself in our texture. When we're ready to save the final texture as a .png, we'll delete the photo layer completely.
I'm sure you can see the benefit of putting the real car over the template, especially if this car had a more complex design.
Now you can perfectly place all of your details, in their own seperate layers. Here, I've added details such as the crown, "O.P.P.", "POLICE", black and white stripes. None of these details are actually sourced from the reference photo. The text is made with the text tool, stripes with the brush tool, and the crown is taken from a different, high-res image (I'll describe how in a future lesson). When we delete the photo layer, the details will remain, in perfect proportions and positions:
Lesson 4: Text & Fonts
Since lettering makes up such a big part of our textures, I've tried to put a lot of info in this lesson. Many of the methods here are also applicable to logos, stripes, or whatever.
Finding the right font:
If you have a sample image, and don't recognise what font is used, you can try asking in the forums, or searching yourself. I have samples of some common fonts below. Identifont lets you identify a typeface by answering a series of questions. WhatTheFont lets you submit an image, and then automatically searches its database. Just remember to crop your example image so that only the lettering is visible.
Note that not all lettering is necessarily a "font", and therefore may not be type-able. An example would be the scripted "Ford" in the blue oval logo. Such lettering would need to be "hand-drawn" (literally or digitally) in order to duplicate.
Font Samples:
These are just some of the many fonts that I use for vehicles, in not-much of a particular order. When making licence plates, "Roadway", "Mandatory", and obviously "Licence Plate" are useful.
Editing the text:
By this, I don't mean editing what the text says, but how it appears. When we input text with the text tool, GIMP creates a new text layer. We can tell it's a text layer by the 'T' icon:
While it's a text layer, we can change things such as the typeface (font), the font size, colour, whether each line is aligned left, center, or right, and the spacing between each line or between each letter. We can also change the word itself, in case we need to correct a typo. If you've closed the text editor box shown in the centre here, you can reopen it by right-clicking the text layer in the layers dialog and selecting "Text Tool".
Some editing techniques will alter the layer in such a way that it's treated like any other layer. From then on, we can't edit it with the tools in the text editor, such as changing font, etc. These methods may be used with things other than text as well, such as logos and stripes, but are especially useful here.
For example, if we need "slanted" text, and there's no italic version of a typeface, we can use GIMP's shear tool to angle it right or left:
After. Note how the layer called "POLICE" no longer has a 'T' icon. This means that GIMP no longer considers it to be a text layer:
Often, the text is either too tall or too short, relative to its width. We can scale the text either vertically or horizontally to achieve the proportions we want. Here, I've reduced the vertical size, in order to 'squish' the text: