I have a
Garmin c330. It's great, comes with North America loaded already, fits on the dash, and is portable. Runs off of an internal battery for 6 hrs. when not plugged in.
For example, I was using ti to go from Philadelphia are to northern NY state. I wanted to stop in a Walmart on the way up to pick up a camping lantern, so I entered Walmart, and it showed my every Walmart on the way up. I waited until I passed one right at the exit of the interstate, jumped off, bought the item, and continued. About 20 minutes later, I went to plug it in so it would be charged when I got to my destination, and it was broken. Did the same thing again, and returned it at another Walmart in NY state. Another camper arrived on their spare tire and needed to find a tire shop, so we found the nearest tire store, and I gave it to them to use off the battery to get them there after marking our campsite location so they could find their way back to the remote location.
On the way up, I drove through blinding thunderstorms with visibility such that I dare not take my eyes off the road to look at the unit. I just listened to the voice commands. Driving in the dark or inclement weather, I can see the intersections coming up, so know where I'm turning before I get there. This is a safety aspect of it that I never even thought of when making a purchase.
The trip logging feature records the maximum driven speed which is handy with my new 16 year old driver. If the car is being driven too fast, I'll know it, even if I'm not in the car. I can see how fast the vehicle is going without being able to see the car's speedometer.
This weekend I'll take the unit with me on Amtrak down to Virginia and use it to drive back. I can even turn it on on the train to find out where we are in the trip.
All that, and it's so simple, you don't need a manual to figure out how to use it. It's money well spent. the unit will pay for inself in saved fuel over time. Get an accurate unit with a touch screen.