I prefer my races to be uninterrupted, so a save progress feature is not what I'm looking forward to. What they should do is reduce the benefit of using B-spec mode if you are mostly a player with a tendency of playing A-spec only. So your B-spec driver will be utterly piss-poor and remain that way if your A-spec-to-B-spec ratio is 4:1 or higher. Your B-spec mode will also be very ineffective with fewer control options, only a fuel gauge to monitor your driver, and no in-/on-car camera views.
If you are a player whose profile is predominantly in B-spec mode (an A-spec-to-B-spec ratio of 1:4), then your driver will learn more than twice as fast as a player using B-spec with a profile ratio of 4:1. You will also get a multitude more of features, such as:
B-spec driver fatigue/aggression meter
oil, tire, and water temperature gauges
faster pit stops or better trained pit crew
obviously much more skilled and faster-learning B-spec driver
Someone with a A:B play ratio of 1:1 will get only a neutral amount of features from either side.
Recap:
Basically, someone who plays a lot of (or purely) A-spec mode will have a disadvantaged B-spec mode with fewer of everything. On the flipside, for someone who plays a lot of (or purely) B-spec mode, they will be rewarded with a much more insightful control over their race team (for a player who wants to play the responsibilities of a race team manager).
Just a thought to separate the A-spec crowd from the B-spec crowd, both of whom have their unique advantages and disadvantages.