Audis used to come with a plastic key which I assume was meant to be used to obtain replacements if the real keys were lost but it was perfect for taking on a dive. Sadly I lost my last one somewhere in the car park at NDAC about 15 years ago. I bought an S3 in 2001 that even came with a 'service' key. It would open the doors and start the car but would not open the glove box so you could stash stuff away from the 'technicians'. This too was waterproof. Sadly, they've abandoned this, even on the more expensive models. However, Santi drysuits have a very nice zipped pouch inside and they are so good with their servicing that they even replaced the one on my E-Lite when I sent it back for a service over the new year 'cos it had got a bit manky (they did it for free, nice one Santi).