Self driving cars. They'll turn right all by themselves to take you on a tour of advertisers. Mandatory expenditure before they'll take you to your destination. Pay more to turn it off...
Waze already does this -- it started with ads for food places nearby/on route and a "drive" button, now it's all categories. Sounds likely that some manufacturer will do this in some capacity. Maybe they'll market it as "recommended for you".
Waze is a mobile phone app that I get access to and maintenance of for free. If manufacturers think they'll get the same reaction from me on a car that I paid $40,000 for, they're in for a nasty surprise.
You're right, I didn't mean to justify this, just that it's been done before in a fitting way. I assume they'll borrow that implementation at some point.