During my time on patrol, I participated in my share of car chases—or “vehicle pursuits” as we called them in official reports. A typical report contained a meticulous recitation of every street traveled, every turn negotiated, every stop sign and red light disregarded. Most often, the report failed to portray the danger, the urgency, or the chaos of the chase. Although we were always directed to “paint a picture in words” for the prosecutor and the courts, our use of legalese—sophisticated coptalk—usually left the image rather cloudy. You weren't supposed to write a thrilling novel but a “just the facts” narrative.
You want the readers of your novel to visualize your chase clearly. Before you write, it may be helpful to diagram your chase using one of the many online navigational aids available such as MapQuest and Google Earth. Following a map lets you establish the twists and turns of a car chase realistically, even down to which street are one-ways, which have media strips, and so forth. If your setting is a fictional place, you can select a localeand simply change the street names and other landmarks. You don’t want to get too complicated. Two dozen turns becomes boring, especially if you fail to inject some action.
Keep your chase scenes simple and intense. Don’t get bogged down in the minutiae of the event itself. You might consider a break in the action, where the chase is broken off, giving characters a chance to think or talk, only to jump the bad guy again and continue the pursuit.
The story is still about your characters, not the chase. Keep your characters in character. If your antagonist is the clever, cunning type, then he should pull some bold stunts during the chase that help him escape. If your pursuing protagonist is a cool, calm cop, then he’s not going to hit the high notes as he radios for assistance from other officers. In a foot chase, a fortyish, slightly overweight cop will either catch the bad guy within half a block or it’s over.
Before you get too crazy with the action scenes like jumping opening drawbridges and driving through showroom windows, keep in mind that police departments have very detailed written policies on what can and cannot be done by officers in a vehicle pursuit. The procedures at my agency fill twelve pages. For example, shooting at or ramming a vehicle would be considered deadly force and would only be justified to prevent imminent loss of life.