CNET:

Many of today’s new cars offer in-dash GPS as an option, and some offer it as standard equipment. The earliest models were CD-based, lacked detail and had a robotic voice. Nowadays, any in-dash system worth its salt is DVD-based, so maps for the entire country have more detail and Malaysian maps will usually fit onto a single disc. In-dash systems are usually more expensive than their portable counterparts, but they usually feature larger screens and integrate better with other vehicle electronics. And even when the signal is lost, the car’s sensors will keep tracking the car on the map until the signal lock is regained.