Interference from car electronics using Widex 440 Clear

I have been trialing the Widex Clear 440 Fusion and the Phonak Adeo S Smart IX (for the 2nd time).
Both times that I have tried the Phonak I have had problems with oscillations being started by specific sounds so I had decided to send back the phonak and keep the Widex.
This week we changed our car to a new Renault Megane and suddenly found that the Widex started picking up interference from the car. It seems to come from the dash board area but it really sets the Widex buzzing!! I quickly switched to the Phonaks and there was absolutely no interference at all.
I love the Widex - crystal clear speech etc, but this car problem might just be a deal buster. I have an appointment with the audi on Monday when I am supposed to be deciding and buying!!
Does anyone have any ideas why the car should interfere with the Widex and is it likely to be something that can be adjusted out?
help - I am running out of time!!!

Hi pbs.

If the Widex has a T-coil, is it accidentally switched on?
My Phonak Naida`s will pick up noise when the brakes or indicators are operated if inT-coil mode.

Only a wild guess………

Thanks for your reply John. I do have T Coil on the button but it isn’t switched on. The Phonaks are OK with the car. Maybe I will get my audi to completely disable the TCoil…