"It is absolutely not true," triple world champion and former Ferrari driver Lauda added.
In his harsh critique of the controversial 'new' face of F1, Ferrari president Montezemolo claims drivers are easing their cars to the chequer because of the new 100kg per race fuel limit.
But Lauda insists Ferrari must simply have not done a good enough job with the new rules.
"In Malaysia, where we were first and second, we finished the race with 5 kilograms of fuel left over," he said. "And other teams were in the same condition.
"Last year, when the Pirelli tyres were so weak and erratic, we had to slow down much more during the race but no one complained then.
"And because of the tyres, we were saving fuel (in 2013) more than now, because a couple of kilos more weight would affect the performance so much. Yet no one said the drivers were 'taxi drivers'," Lauda charged.