Money and budget in modern days race drivers live: I think for a modern time career there needs to be some sort of budget / reputation simulation to advance to better teams (which could be emulated already now with custom ai) or higher classes. Nowadays, already in young age, the drivers are full with sponsor advertisement, like the local furniture store, drinks, equipment deliverer, .... I like the mechanics of choosing a sponsor and connecting its payment to a bet on the outcome of a series of races (duration of the contract), e.g. take the small advertisement and you need to finish top10. Take the big one and you need to finish top5 in order to get there support / money. Configurable career mode: With the different tastes people have regarding which part of motorsports racing should be in the career, the only way I see to deliver the best career experience is by customization. Every feature, as for instance the lap time trophy challenges mentioned above (@TronLi I would enjoy those as well to have some variations in the std career) or the proposed sponsor system, should be optional and can be added or fine tuned when setting up the career.