Car manufacturers, new car dealers and new car buyers are all getting stitched up by the new EU6d TEMP / WLTP Emissions Standard from September 2019. There weren't enough test facilities to test every variation of every new car anyway, but if a car fails the test and has to be revised it goes to the back of the queue and that's what creates the delay. There are some stocks of some cars that don't meed WLTP and they can be sold up to 31 August. Also, if a car tested to WLTP standards has much higher emissions than it had on NEDC, that means its first year tax is much greater. Some cars, such as Kuga, are being sold like this, but not Tiguan. If you are getting cold feet, tell them that since they cannot deliver the car, you are not prepared to pay for it so they have to refund you the scrappage allowance they gave you for your old car (or return the old car) and wipe the slate clean. Give them the alternative of taking your payment and then supplying you with an equivalent car until your new car arrives.