There have been concens that car sharing could affect someones motor insurance policy. I am happy to say that The Ramblers encourages car sharing & it should have no adverse affect on your motor policy. Car sharers may also make a contribution to the driver towards fuel costs. The important thing is that any contribution is clearly VOLUNTARY.

this is the link to the Ramblers insurance on the web site

you should click on "here" then go to section 3.3.7

 this is an extract of the relevant page

 
3.3.7 Transport to and from walks
Ramblers insurance does not cover travel to and from walks, meetings or events. For chartered coaches, or public transport, insurance cover is a matter for the transport operator. 12
As an alternative to public transport some Areas and Groups operate car-sharing arrangements where walkers meet at a convenient point and then get to the actual start point of the walk itself in shared cars. The Ramblers supports car sharing as a means of reducing the environmental impact of driving to walks. However, Ramblers insurance does not cover any incident arising as a result of car sharing.
Ordinary private motor insurance covers drivers giving lifts to others. But this cover is invalidated if a fare has been charged for the journey so volunteers must take great care about the way car sharing is arranged and publicised.
Many Areas and Groups suggest in their programmes and other publicity that passengers in a car share should make a contribution to the driver towards mileage costs. This is fine as long as it is absolutely clear that passengers are being requested to make a voluntary contribution. It is also fine to suggest a level of voluntary contribution that may be acceptable (e.g. x pence per passenger per mile).
If the encouragement to pay drivers appears to be more like an instruction or a condition rather than a voluntary contribution, it is possible that this could constitute a fare, which in turn, would invalidate private motor insurance.
A suggested form of words for publicity is:

Our Area/Group encourages car sharing and walkers often meet at x car park. Drivers often appreciate it when a voluntary contribution is made by passengers. As a guide, x pence per mile per passenger is considered an amount which reasonably covers the costs incurred by the driver.