Most people use PHP "include" files.
You have separate pages for different content, like body kits, spoilers, hoods (use one page as a template and edit the content for the others, saving with a .php extension instead of .html).
In every page you have PHP code to include the bits that repeat on every page, like a header, logo, menu bar, footer with code like <?php include ("header.inc"); ?> in the places where the html markup would normally go
You create separate "include" files for each of the common bits, just the html markup without doctype, html, head or body tags.
See http://www.wickham43.net/serversideincludes.shtml
Code downloaded to my PC will be deleted in due course.
WIN7; IE9, Firefox, Opera, Chrome and Safari for Windows; screen resolution usually 1366*768.
Also IE6 on W98 with 800*600 and IE8 on Vista 1440*900.