Two paint protection companies have been told to amend their marketing materials after they failed to prove product claims to the advertising watchdog.

Claims by GardX and Jewelultra that their motor paint protection products help to protect against damage from bird droppings have been judged misleading by the Advertising Standards Authority.

It means that current point of sale materials and sales procedures used in car dealerships could need changing.

After a challenge was initiated by Autoglym, a rival car care and paint protection provider, the ASA asked GardX and Jewelultra to provide evidence to support their marketing claims.

In its official statement, the ASA said GardX had tested the efficacy of its product against acidic and alkaline solutions. However their material specifically claimed it could delay the corrosive effect of bird droppings and therefore the ASA expected GardX’s evidence to have tested for performance in that regard.

However such tests had not been conducted, and did not meet a recognised ISO standard assessment, so the ASA has concluded GardX's bird dropping protection claim has not been substantiated.

Jewelultra said its Diamondbrite product was tested during development in the late 1980s in relation to resistance to bird dropping damage and, although it no longer had copies of those test reports,  its claims of proven to protect against bird dropping were based on those results.

It provided a technical report of independent tests conducted in 2011 related on its ability to protect against general weathering, but this had not tested against bird droppings.

The ASA said advertisers must hold documentary evidence to substantiate claims, and Jewelultra had failed to do so, therefore it ruled the claims could not be substantiated.

Both GardX and Jewelultra have been told not to allow the claims to appear again in their current form.

Jewelultra said it has now commissioned tests specifically in relation to whether Diamondbrite protects against bird droppings.

Paint protection products are a favoured add-on sale for sales executives due to the profit margins they can provide.

Autoglym chief executive Paul Caller said consumers have a right to expect products to deliver on their promises, and this raises an important issue for retailers and dealerships as to whether they can risk potential damage to their reputation if they choose to sell products that have been judged to mislead customers.

“We believe it is vital to be clear and accurate with customers and are pleased that suppliers of paint protection products in the UK will now be required to operate on a fair and level playing field," Caller added.