Holden Captiva 2012 Problems

I can't comment on the Walkinshaw chip specifically, I don't have any experience of it, but I'm not a huge fan of the chips in general as you don't really know how they achieve the results they claim, and ultimately you don't know what effect they will have on the car down the track. If you can find someone who has fitted a Walkinshaw chip you could ask them, after all first hand knowledge is the best you can get.

You have experienced the problem that is the fuel consumption guide. The fuel consumption in the ads and the guide are the results of tests done under laboratory conditions, and not necessarily an accurate guide to what might happen in real life. They are meant to be used to compare one make and model against others in the same class, they're not intended to be an outright measure of real life fuel consumption. That gives carmakers the wriggle room they need to get out of a problem when customers, like you, complain. I think you are within your rights to demand that the dealer/Holden thoroughly check your car instead of fobbing you off and make sure it is within the factory specifications. Once that is done you could test your false advertising allegation, but that's a legal question best answered by others. I do, however, have some sympathy for your view.