The entry level Garmin 250 car sat nav is a very good entry level gps unit with a 7.2 x 5.4 cm display and approximately 5 hour life from its rechargeable lithium ion battery. It has an internal speaker, a number of different ways to calculate routes (fastest, shortest, avoid tolls or highways) and will even act as a world travel clock and currency converter.

If, however, you have a bit more money to spend, the Garmin 770 will offer a great deal more.

Take, for example, the pre-loaded maps. Where the Nuvi 250 comes with European maps, the Nuvi 770 has maps of eastern and western Europe as well as North America. But the overall list of features of the Nuvi 770 is where it wins, hands down. It has a larger screen than the 250 (9.7 x 5.7 cm), it speaks street names in a choice of downloadable voices (including Elvis Garmin and de Niro Garmin at extra cost) and has Bluetooth connectivity for hands free use with your mobile phone. You can dial the phone number you want on the touch screen and you just have to tap the screen to receive any in coming call and can talk using the built in microphone.

You can choose the keyboard layout you prefer (ABC or QWERTY) on the touch sensitive screen of the 770, it will act as an MP? player and even link to your car radio with an FM transmitter(if you are going to use this function, it is best to check which countries you can use it in; Greece, Italy and Slovenia are ok, but in others low power FM transmitters aren't allowed).

The Garmin 770 also has static speed camera locations pre programmed into it and will warn you as you approach one that is on its database. However, if you are going to use the 770 in Europe, you should probably turn this function off, as it isn't legal to use any such warning system in most western European countries.

Probably the most important feature of the Garmin 770 is it's TMC traffic receiver with a European life time subscription. This means that, any reported traffic problems, such as road works or traffic accidents, on or near your planned route, will be reported to you and you then can decide to avoid them or not simply by tapping the screen (UK traffic subscription extra).

If you have a number of sales appointments or deliveries to make, you can program them into the nuvi 700 and let the unit calculate the most efficient route for you. When you get there, if you have to park in one of those huge surface car parks, when you remove it from the windscreen mount, it automatically remembers where you left the car so you can navigate back to it.

So, you can see that the Nuvi 250 is an adequate sat nav, but for a bit extra, the Garmin nuvi 770 is a feature packed, mid range unit.