Hi Dan,
If you can find a place to mount the tablet in the vehicle such that you don't have to take your eyes off traffic to glance at it, it should be great for in-car navigation assistance. Take a look at the
List of laptop GPS navigation software programs and reviews for some ideas.
How are you planning to deal with navigation when walking and cycling? Planning to print paper maps to carry along? Carrying a laptop, even a small one, isn't a particularly useful option if you want navigation help in real time or at least quickly. I have found that for personal navigation to be most useful it has to be as handy as a paper map. That means I don't want to have to wait for a machine to boot up or resume, load nav software, get a lock on satellites and so on, every time I want some information about where I am, how to get from Here to There, or what's around me (POIs).
When walking or cycling, if your tablet has an instant-on feature like handheld personal navigation devices it will be useful for checking for nearby points of interest. If not, a handheld personal nav device might be a better option.
When walking or cycling, if the tablet can be carried in such a way that your nav software can maintain a continuous lock on the GPS satellites and show you a "moving map" picture of your progress it will be useful for real time navigation assistance. If not, a handheld personal nav device might be a better option.
Does your tablet have an integral GPS receiver or will you have to get one for it? If you need to get an external receiver for it, seriously consider one that connects wirelessly with Bluetooth. For walking and cycling you don't need the nuisance of a wired connection between the tablet and the receiver.
For in-car use, a wireless connection between the receiver and laptop also gives you a lot more flexibility to place the GPS receiver where it can get the best view of the sky and place the laptop for best driver access, without regard for the length and routing of a connecting cable.
If you are interested in getting all of your needs met by a single supplier whose maps cover most of the world, with laptop software for trip planning, points of interest and realtime navigation, and with a variety of handheld personal navigation devices that can use the same maps as the laptop, Garmin is one supplier to consider.
But I recommend that you take a look through the post that I linked above to get a feel for the various laptop solutions available, and then think about whether a laptop solution, even with an ultraportable, is going to fill the needs for walking and cycling. There are forums on here for each of the laptop products listed. Each of the forums has experienced users who are happy to answer any questions you have. And some of the forums even have vendor tech support people who drop by from time to time.
I hope that helps you get a little farther down the road. And :welcome: to Laptop GPS World. I hope your visits are informative, or at least interesting.
...ken...