Sat Nav Features
The newest sat nav units can do far more than talk you through your journey. They can warn you about 'safety cameras', and act as a hands-free telephone or MP3 player.
Your sat nav unit comes loaded with a detailed set of road maps - for instance, covering the UK and Ireland. So if you think you might take your car to Europe, and want to use your sat nav there, you should consider getting European maps as well, but check whether your usage will justify the price. Maps are some of the most expensive elements in sat nav units: the bigger the area of coverage, the more you will have to pay. (Note that many brands of sat nav will also allow you to purchase extended map coverage at a later date.)
Points of Interest
The maps on your sat nav unit may also include icons showing 'Points of Interest' (POIs). These may cover a broad range of places, such as petrol stations, car parks, vehicle repair centres, cashpoints, restaurants, hotels, shops, museums, post offices, emergency services, parks and cinemas. A few of these will appear on screen as a matter of course; others you can find by accessing your sat nav's pre-installed database. POI databases vary from model to model: for instance, some hold details of chain restaurants and shops, other specialise in historic buildings, galleries and museums. Your sat nav unit may well also permit you to extend your POI range with 'custom POIs', produced by specialist companies that gather and publish Points of Interest tailored to specific requirements.
Fuel and park buttons
Many sat nav screens will mark petrol stations and car parks on the maps, but some have 'fuel and park buttons' which only bring up these details when you request them.
Safety camera locators
Many sat nav units now also include information about the location of 'safety cameras' - speed cameras and red-light cameras (at traffic lights). A voice warning or sound signal alerts you to upcoming cameras, and may inform you of the correct speed, to prevent you from landing a costly fine for infringement. (This facility is entirely legal.)
Upgrades and downloads
Roads change: new ones are built, some turn into one-way streets, right-hand turns are made illegal at certain crossroads, new safety cameras are installed, and so on. The sat nav companies have to update their software constantly to take account of these changes - and, likewise, you will have to judge how often you need to update your system to keep abreast of the changes. This can be done by computer downloads and memory cards, or by GPRS phone connections or DVDs (in the case of built-in or 'hard-install' sat navs) - but, needless to say, there is always a price to pay.
Live traffic information
Sat navs in the higher price range often include a connection to a broadcast system that relays up-to-the-minute news about traffic conditions and congestion that might affect your journey, and they can also alter your route to avoid such problems.
If the light illuminating your sat nav screen remained constant, it would seem glaringly bright when driving at night, but perhaps too pale to see against bright sunlight. Sat sav systems therefore have built-in sensors that adjust the screen brightness to take account of the light conditions outside; this is known as 'auto-dimming', or 'anti-glare'.
Some sat navs are designed for walkers and runners (as opposed to vehicle use), and are powered entirely by batteries. Car sat navs can perform the same function when removed from the car, if fitted with batteries. Manufacturers will often cite the 'stand-alone battery time': this is the amount of time that a sat nav unit will operate when powered only by the batteries. Remember, however, that sat navs work properly only when they can 'see the sky' and can connect with at least three satellites - so they do not work inside buildings.
In this age of multi-function gadgetry, sat nav manufacturers have seen the opportunity to add a host of other uses to their units, especially models in the upper price range. After all, with a sat nav you already have a screen, plus sound and digital technology. Some units therefore allow you to attach an MP3 player to it (via a cable), so you can listen to music or pod-casts. Some have music pre-installed, or have connections to XM satellite radio. Others even allow you to download photos from a digital camera, so you can edit and look at images and watch a slide show; and with some you can use the screen to watch DVDs (presumably not whilst driving).
Hands-free mobile phone
Some more up-market sat navs also act as hands-free mobile phones. Equipped with microphones, they use Bluetooth wireless technology to link up with your mobile phone. (You may need to upgrade your mobile phone, or contract, to do this.) This is clearly a facility worth considering now that the law against using hand-held mobile phones whilst driving is fully enforceable, with heavy penalties for infringement. Some sat navs fitted with this technology will even read out SMS text messages for you.
If you don't like the voice that gives you your sat nav route instructions, you don't have to stick with it. Using CDs or downloadable software, you can be guided by just about anyone you choose, from the stars of TV and the movies and famous politicians to comedy sergeant majors and Norfolk chicken-farmers.