les per gallon. For vehicles with a higher ratio (<code>drat == 4.93</code>), this reduction in fuel economy is lower at 7.27 miles per gallon. Yet this is also not fully accurate because it mixes the automatic and manual cars, so we may want to further break out the results by transmission type.</p>
<p>The <code>at</code> argument accepts multiple named combinations of variables, so we can specify particular values of both <code>drat</code> and <code>wt</code> and <code>am</code> for which we would like to