A judge hearing a case over whether Shell's advertising campaign for a fuel additive was misleading has reserved his decision.
Shell has been before the Wellington District Court this week defending 22 charges laid by the Commerce Commission under the Fair Trading Act.
The Shell advertising campaign claimed its Fuel Economy Formula was 'designed to take you further'.
The Commerce Commission says the ads were misleading, as tests showed using a tank of the fuel only increased the distance travelled by less than 1%.
However, Shell said the commission and its witnesses acknowledged the claim made about the fuel was literally true.
Its lawyer said Shell was the only company to have proven a fuel economy benefit for its additive and was proud of its achievement in developing such a product.