Combine that with expensive Audi parts, expensive and zealous dealership labour, and they are unbelievably expensive to maintain.
I own a 2006 that I bought for a song--I do my own service, so I was willing to take a bit of risk. The cars are very difficult to work on, even an oil change involves special tools and working around a poorly laid out engine bay. It takes me twice as long to do as any other car I've done.
The previous owner of my car put 120,000km on it. I only have the last 50,000km or so of records, but in that time it was towed to the dealer at least twice according to the service records, and she spent upwards of $10,000 on regular service ($250 oil changes? yep) and fixing broken stuff that shouldn't break at that mileage (turbo blowoff valve, ignition coils on more than one occasion, brake lines, the list goes on). She spent over $1000 on every trip to the dealer in that time.
I do not understand anyone who buys a new Audi, or for that matter any German car. It's ridiculous.
https://electrek.co/2016/06/06/tesla-model-s-battery-pack-da...
The only VW in the same platform (B) as the A4 is the Passat, and there's a lot less shared components between the A4 and Passat than there are for platform A models.
Brake pads should last a little longer, but I'm not sure how much.
Ultimately though I believe electric cars will be much more expensive in the long run. Nissan wants $5499 for a new battery back. I don't know of any study on how long they last, but reading forums and extrapolating I would say you should plan on replacing the battery pack every 100000 miles. This of course depends greatly on how your charge it which in turn depends on how far you drive. If you drive the full range of the battery every charge you probably need to replace the battery every 50000 miles. If you make dozens of short trips per day, charging after each, you could potentially get several hundred thousand miles.
I'm curious about your A4 experience - how many miles were you driving. Unless you are driving 80,000 miles a year I don't see how you can get that high - at 80,000 miles/ year you have timing belt service. If you are driving this many miles the VW diesels (same base platform as the A4, though less luxury) can probably pay for the entire car including maintenance just in fuel savings.