Soon after we bought it our 2015 Kia Cerato developed a violent shake in the first 20 seconds after it's started and the revs start to come down. The car has been to two dealerships and Kia Australia has also been involved. Kia had the car on a data logger that confirms that there is an issue, but claim it's within emission standards and to persuade – their words – the customer to accept the vehicle as is. This is a very upsetting situation; they are basically telling us there is nothing wrong with the car. I'm at a loss as to where to from here.
The problem needs to sorted out with the dealer and Kia, so go back and tell the dealer you are unhappy with the car as it is and request them to fix it. Tell them you will not accept the car as it is. Ask them to demonstrate on another Cerato that the problem is 'normal'.