What you need is to concentrate the focus of the page on the keyword.

It's not just about whether the keyword appears in your content. It's about how much emphasis you give it.
is it at the start of headings? is it in link texts? is it in images? do you have stop words?

Here's a technique that has worked for me: for any single phrase (eg.: car sales) I build one page where -
- url is SE friendly version of the phrase (site.com/car+sales/)
- title is the phrase (<title>car sales</title>)
- phrase is at the start of description meta tag
- phrase is at the start of keywords meta tag
- h1 is the phrase - matches title (<h1>car sales</h1>)
- h2 is variation of or contains the phrase (<h2>cars on sale</h2>, <h2>cheap car sale</h2>, <h2>online car sale</h2>)
- when possible, all links to the page use the keyphrase (<a...>car sales</a>)
- at least 3 <strong>/<em> occurrence of phrase within paragraph text (<strong>car sales</strong> and <em>car sales</em>)
- The keyphrase appear in one of the first 2 and one of the last 2 paragraphs of the document
- there's an image using the phrase in its source and alt text (<img src="/img/car+sales.jpg" alt="car sales"/>)
- the page links to itself with the title of the page

PS.: for a phrase like "car sales", it's tempting to use stop words like "cars for sale" or "cars on sale" and it's important to structure your content so you can avoid these. words like "the", "and", "a", "for", "or", "in" and a few others do nothing but diminish the density of your keywords within a phrase...