The AA in the UK has issued some useful advice on avoiding buying flood damaged cars.

With floods affecting large parts of Ireland and the UK over the holiday period tens of thousands of cars have been damaged by flood water.  70% of flooded cars are written off by insurers, but there is an increasing trend for owners to avoid making a claim and try to sell their damaged vehicles to unsuspecting buyers.

Once dried out many flood damaged cars look fine on the surface, but may be hiding potential long term problems. The AA has listed some tell-tell signs to look for:

• Are any of the windows open on the car when viewed. The seller might be trying to ventilate a damp or drying interior.
• Is the seller making excessive use of air fresheners.
• When inside push down on the carpets for signs of damp.
• Check the condition of the brake and suspension components. Do they look more corroded than expect of a vehicle of this age.
• Is there any unexpected or unexplained corrosion around the engine bay? Unscrew the oil filler and look for a white, mayonnaise-like emulsion on the underside of the cap. Its presence could suggest water in the engine oil.
• Check that all the warning lights are working. Start the engine and ensure all lights go out.
• Ensure all electrical items are working. 
• Do the windows steam up excessively on the test drive? This may be due to moisture from flood damage.
• Get a car history check and an independent assessment if serious about a purchase.