By pleading not guilty, does that mean my case will go to trial or can it still be handled out of court?

So I got pulled over in October for a DUI, and my arraignment is tomorrow morning. My lawyer said something about getting it bumped down to negligent driving, but I’m not sure how that works. All I know is that there’s an extra $3,000 added to my lawyer bills if this shit goes to trial and that we’re pleading not guilty tomorrow. Basically, what are the chances of this going to trial? By pleading not guilty, does my case automatically go to trial?