What should I look for in an in-dash navigation system?

Accuracy, speed, and ease of use: If you read reviews of various navigation systems, pay specific attention to the author's opinions of the navigation accuracy, the relative speed of route calculation and recalculation, and the ease of working with the screen's control interface (most in-dash navigation systems feature touchscreen controls). These are all elements which can't necessarily be quantified in a specifications chart, but are vitally important to your overall enjoyment, and to the system's utility.

In-dash navigation systems install cleanly in your vehicle's console.

Screen size and resolution: Perhaps the most appealing aspect of an in-dash navigation system is the size of the screen that shows the maps you'll use to get where you need to go. Hardly surprising, the bigger the better. Most are either 6-1/2 or 7 inches (measured diagonally), either of which will give you excellent, at-a-glance visibility. You might also want to compare the resolutions of the screens you're considering; the higher the resolution, the sharper the picture, and the easier the map information is to see.

Internal memory: Internal memory lets you play music while you're navigating. The memory saves the route you've programmed, so you can remove the map disc and use the slot for your CDs or DVDs. A bigger internal memory means that more map information can be saved at a time. This is particularly helpful in route recalculation. With a large internal memory, you won't have to re-insert the map disc if the system needs to reroute you because of a missed turn, construction, traffic jams, or other problems. If you're really getting into the nitty-gritty of systems you're considering, you might want to find out the systems' processing speeds. Faster processors help the system calculate and recalculate your routes quickly.

Points of interest: Points of interest (POI) are some of the most useful features in any navigation system. They help you find various locations in unfamiliar towns, including restaurants, hotels, gas stations, even ATMs. The more POI a navigation system has, the more options you'll have when you're on the road. Many systems let you program several stops along the way to your destination. Look for this feature when you're comparison shopping.

Real-time traffic data: Some systems are compatible with real-time traffic services. For a monthly fee, you can receive real-time traffic information, including traffic jams, construction, and even average speed of traffic along the programmed routes you're traveling. This doesn't just benefit cross-country travelers — it's especially handy for people with long commutes to and from work. Currently, traffic services are limited to major metropolitan areas, and typically require extra hardware.

Touchscreen controls: All you have to do is tap the screen in the appropriate spot to enter a command. Touchscreen controls make entering destinations easier: when entering a city, for example, the touchscreen system will present you a virtual keyboard. As you enter letters, only the letters that could logically follow are presented, and suggestions are offered once you've reached a certain point. This saves you time, and is one of the many benefits of touchscreen controls. Most in-dash systems, fortunately, have them.

If your vehicle has a double-sized dash opening, there are systems that will fit it perfectly.

Dash opening size: Some in-dash systems fit standard dash openings (called single DIN), just like standard stereos. Others fit the oversized (4") dash openings that you often find in Japanese vehicles (double DIN). The monitor of a single-DIN retracts into the chassis when you turn the power off, then motors out and flips up when you're ready to use it again. The screen of a double-DIN sits flush in the dash, as though it were a factory-integrated component. Single-DIN screens are either 6-1/2" or 7" diagonally. Double-DIN screens typically are measured at 6-1/2". For the most part, the one you'll need depends on the dash opening you have (although, if you prefer a retractable screen, you can use single-DIN systems in many double-DIN openings with the help of an adapter kit; double-DIN systems will only fit double-DIN openings).

Since these systems play audio and video, check out our Mobile Video Shopping Guide for ideas on what to consider from those angles.