GPS for car and bike use

[Martin]

Manotea clamps his to the steering wheel (it has a recess) which is probably the best place given the screen size

Just a thought- is it in the airbag zone ? 
If so, you might want to consider moving it in case it gets launched at your head.

no it clamped to the top rim of the actual wheel (so no use in police car chases)

Clamped where ?  It must have been April 1st.  Set into a 'spoke' possibly but not on the rim.

Rim of the car steering wheel 

[Plax]

My partner has a Garmin Nuvi 250 for his car. It has options also for pedestrian and cyclists. You can also get a bicycle mount for it.
Battery life is only about 4 hrs though, so for long rides you might need something like a power monkey (or whatever you call them).
Also have the problem of it not being waterproof.......(can always stick it in your pocket and listen to the directions I suppose!).

[frankly frankie]

Nuvi 500 and 550 are waterproof, I think.