(Business 2.0) – The latest receivers for your car move with you in a whole new way. All the key features for easy navigation—touch-screen controls, spoken directions, and street maps for the entire lower 48—come packaged in pocket-size models that easily transfer between cars or slide into a suitcase. But the best add superior ergonomics and features that really take them (and you) the extra mile.

TomTom One XL Weight: 7.4 oz. Dimensions: 5 by 3 by 1 in. $400; www.tomtom.com [3 STARS]

PROS "Portable" and "big-screen" may seem contradictory, but TomTom has pulled it off with the XL, whose main selling point is its clear and bright 4.3-inch high-resolution display. The turn-by-turn voice instructions get louder as you accelerate, and traffic conditions can be beamed to the Bluetooth-equipped unit via your mobile phone.

CONS TomTom's software needs some work. Its main menu has too many choices to show all at once, so you have to take your eyes off the road to page back and forth. Similarly, should-be-simple tasks like finding the nearest ATM or parking lot take half a dozen taps on the screen.

BUY THIS ONE IF ... The demands of middle age require a supersize screen.

Garmin StreetPilot c580 Weight: 9 oz. Dimensions: 4 by 3 by 2 in. $750; www.garmin.com [3½ STARS]

PROS The StreetPilot will please both Luddites and tech geeks. The windshield mount is straightforward and strong; a simple main menu asks you basic questions—"Where to?"—and guides you with spoken directions that include street names. Delve into the c580's advanced capabilities and there's even more to like: You can link a Bluetooth phone for hands-free calls or see gas prices two exits down the freeway courtesy of MSN Direct (free for 12 months, $50 per year thereafter).

CONS The StreetPilot is relatively bulky and heavy, and considering the price, its screen is too small at 3.5 inches.

BUY THIS ONE IF ... You're willing to pay top dollar for best-in-class functionality and an idiotproof interface.

Magellan Maestro 3100 Weight: 6.5 oz. Dimensions: 4 by 3 by 1 in. $300; www.magellangps.com [3½ STARS]

PROS This no-frills device delivers solid performance for the money. The Maestro's antiglare screen offers good graphics, while a pleasant electronic bell alerts you to your next change in direction. Give the Windows Mobile 5.0 software some credit too: Changing the volume or switching between map and text views can be done with a single tap on the screen.

CONS The 3100's windshield mount is overcomplicated and hard to pack. Its small speaker lacks oomph, so it's tough to hear directions with your windows or sunroof open. And unlike more upscale devices, the 3100 doesn't offer a traffic-monitoring option.

BUY THIS ONE IF ... You want a bargain-priced just-get-me-there device.