The advice comes from the Director of the Automotive Development Centre of Universiti Teknologi Malaysia's Mechanical Engineering Faculty, Professor Ir Dr Azhar Abdul Aziz.

Azhar said that so far, most gadgets that claim to reduce petrol consumption found in the markets were not effective.

"As consumers, they should ask for scientific evidence, like the performance chart," said Azhar.

"They should not be misled by data that is gathered from abroad because the situation there might not be the same as in Malaysia."
He said manufacturers should test their products' performance in Malaysian conditions before selling them.

"Consumers should choose products based on their performance and reliability, as well as whether there is a warranty for the products."

Azhar, who has been researching and testing such products, said most of them were effective only for certain types of engines and the reduction in fuel consumption was only between three and five per cent.

"Only a small number of the products are value for money, in the sense that they are able to save up to five per cent of petrol consumption."

As such, he advised consumers to only buy products which had been scientifically tested, for example, by Sirim to ensure quality.

"These products or gadgets have a life span and are not guaranteed by the engine manufacturers as they are not original equipment manufacturer's products," he added.