Which? has revealed the best way to wash your car, and the costly mistakes that are easy to avoid. "With the weather finally starting to warm up, what better time to give your car some TLC?" the consumer champion said.

"It's a job that's surprisingly easy to get wrong, though. Car washing is a common way for drivers to damage their own cars. Done incorrectly, it can result in scratched or marked paintwork.

"However, with the correct equipment and proper technique, you can keep your car looking its best in the short and longer term."

Which? warned not to wash your car in direct sunlight: "Water on your car's bodywork will evaporate much more quickly than you can dry it when the metal is hot, which will leave ugly watermarks.

"If it's particularly warm, the soap could also dry out before you've rinsed it, which will make it much harder to clean off.

"Once your car is clean and shiny, if possible avoid positioning it under a tree, where it will get covered in sticky sap and bird poo, or near sources of dust such as building sites."

Which? also urged drivers to avoid automatic car washes: "The fast-spinning rollers can collect dirt and grit from previous cars, which may cause fine scratches or 'swirl marks' in your paint.

"These are more noticeable on dark-coloured cars, but will make the paint on any vehicle appear duller over time."

They also advised against self-service car washes. The best way to wash your car is with a clean bucket and sponge, car shampoo, and an outdoor water source like a hosepipe.

Do not use washing-up liquid or kitchen sponges on your car. The sponges are too abrasive, and the washing-up liquid can damage a car's paint over time.

Which? said to follow up a wash with a polish and wax. Though it sounds unnecessary, this can reduce the appearance of blemishes and fine scratches and add a protective layer to the paint.

The site also said to only clean your car's interior with a vacuum, duster and damp cloth - avoiding lotions marketed as giving 'cockpit shine' but can actually cause hazards through greasing up surfaces.