First of all, sorry for the long post 
I know there’s going to be some kind of advertising/marketing mechanic in the game and that the devs are still thinking about it (maybe haven’t even begun thinking about it). I work in advertising and my agency works for Audi, so I decided to share some insights on how advertising works in the car industry.
I’m no game designer and I know nothig about game design. What I’ll try to do is explain how it works in real life and then describe how I would create a reasonably realistic simulation of car ads. Basically its just food for thought.
There are essencially two kinds of products - emotional and rational products (my naming, other ad people will call it something else).
Emotional products are things like clothes, beverages, perfumes etc. these are products that can’t be compared. Some people will prefer one perfume over another, but you can’t really have a reasonable discussion about which one is best. It boils down to taste. There is only one way to advertise these products. Branding campaigns. These campaigns usually try to create a connection between the product (or brand) and a given lifestyle. Since you cant diferentiate between a pair of jeans by Levis or a pair of jeans by Diesel, the diferentiation IS the adverting, the branding.
Rational products are things like computers, smartphones and CARS. These are products easily compared. A computer will have a faster processor than another, period. Because its so easy to compare these products the purchasing process is very rational. You will compare two products, decide which one is better, then buy it. Cars are a particularly rational purchase, because they are so expensive. No one will easily part with months worth of their income.
For these reasons, the best way to advertise rational products are not branding campaigns, but campaigns about features. Diferentiating features. Think of Apple, this is what they always do. They usually advertise they’re fantastic OS (there’s an app fot that) or their high resolution displays (retina) etc. Does this mean you should never make branding campaigns? No. Even Apple did one once (Think different). The thinking goes like this - You dont get people to try your products because they love your brand, you get them to love your brand by convincing them to try your products. Which basically means, you better deliver on your promises. If you advertise that your computer is fast, it better be.
So this is how I would create a simulation for automation (again, I’m no game designer, take this for what it is, a fan’s idiot suggestion 
):
First, the Media Plan: You select which media you’re gonna buy.
Print, Radio, TV, Outdoor and eventually Digital.
For each media you select targetting - generic, female, sports, fashion, business and youth
Finally you select how much of each media you’re gonna buy.
Second, the strategic plan: You select what kind of campaign you’re gonna make.
Branding - Increases notoriety and reinforces your positioning (as a sports brand, for example)
Product - You choose the model you want to promote and the feature of that model you think sets it apart (if you choose to advertise the safety of a car that is unsafe, the campaign would backfire).
Promotion - You select the model you want to promote and how much discount you’re offering on its price (this could be useful if you’re introducing a new model and want sell the remaining stock of the previous one, for example).
And thats it 
Hope this is of some use, and again sorry for the long post.