Two Horfield friends are attempting to drive 4,000 miles from Bristol to Istanbul and back in a £200 second-hand car.

On Saturday Gareth Browning and Mark Robson will set off in their 15-year-old Honda Concerto, which was recently damaged in an accident and has an engine light on which no garage can diagnose.

They are asking people to pick a mile between 0 and 4,000 when they think the car will break down. The person with the nearest guess will win half the prize pot, with the other half going to CHICKS (Country Holidays for Inner City Kids).

This is a charity that provides disadvantaged children with a free respite break away in the countryside in Devon.

The housemates, who live in Northville Road, decided to make the journey to Turkey, which they have called To The Bul And Back for "something interesting to do this summer".

Mr Browning, 27, who works in insurance, told the Evening Post: "Mark is a teacher so gets lots of time off over the summer, and I can get three weeks at a time, so thought 'why don't we do something a bit different'.

"So we thought we'd go on a little trip; something over land, and thought the best way was in a car. We don't have much money so wanted to make it as cheap as possible, so we managed to find an old banger at a garage for £200.

"It was taken in by the garage on part-exchange and they wanted to get rid of it."

Mr Browning, and Mr Robson, 31, a teacher at Hanham School, have just three weeks to travel to Istanbul, through Belgium, Germany, Switzerland, the Alps, northern Italy, Croatia, Greece and Turkey.

"We will be camping in some places, staying in cheap hostels in others and trying to collect as much money along the way as we can," added Mr Browning.

"We hope we will make it back, but there could be some breakdowns along the way. I think the £75 breakdown cover will be well spent.

"We've both done a lot of travelling before, but nothing like this. Mark has done three marathons this year for charity.

"We chose CHICKS because it's a local charity, and you can really see where the money goes."

The friends have managed to raise about £650 so far, but have a target of £2,000.

To pay £5 to enter the sweepstake, go to www.justgiving.com/tothebulandback. In the comments box include the mile you think they will break down and an email address so they can contact you should you win.