In this interview about Borderlands, Randy Pitchford talks about the importance of the "feedback loop" in games like Diablo 2. He muses that the game was so enjoyable largely "because of the compelling, compulsive feedback loop of growing my character and becoming a bad ass".
More and more, shooter gameplay is being mixed with RPG-style character progression and customization. Borderlands, Mass Effect 2, Alpha Protocol, The Agency and many others have done this in their own ways.
How might racing and RPG gameplay be mixed?
There are already similarities. Vehicle customization is like gear customization in that the player operates most vehicles in basically the same way while vehicle stats (grip, acceleration, speed, etc) affect style and performance. There's also progression in that the player acquires new vehicles and options for those vehicles.
But some of those similarities are only skin-deep. Customizations cannot be carried from car to car. The same may be said of items in RPGs, but new gear is acquired much more frequently in RPGs. Customizations are more personal in RPGs. Almost every car can be customized in the same ways, and most of those are purely graded (worse to better): exhaust, tires, engine, etc.
Anyway, here are some ideas of how I might design a racer-RPG hybrid.
Create a growth experience with only one or a few cars, instead of encouraging the player to swap out cars or buy new ones. Imagine selecting your vehicle at the beginning of the game and experiencing a whole adventure with just that vehicle. The car is like a companion. It's adorned inside and out with reminders of events. It might even bear scars (until repaired). As the driver improves, it is improved. The player's character talks to the car while driving.
Competitors are not faceless. They are seen. They are heard. And they, too, stick to one vehicle each... vehicles with their own reminders.
Realism isn't ignored entirely, but it takes a back seat to making customization truly personal. If five players all choose to play through the game in Car A, they're customization choices should be different. This personalization of vehicles is in addition to the dynamically-achieved trophies and other reminders of experiences acquired during each player's unique adventure.
The game isn't just racing. Like in an RPG, there are a variety of activities, and not all are sought by the player. For example, the player might be casually driving down a highway or through a city when one or more vehicles start to chase, perhaps even try to ram him off the road. Events like these would be dynamic and not strictly scripted. So what vehicles the player is being chased by might vary, as would where the player happens to be when the chase begins and how the chase ends (perhaps the player or enemy is run off the road, involved in a traffic accident, or police get involved).
What I'm basically proposing is a vehicle-based adventure as opposed to typical driving games.
P.S. Yes, there's more than one pun in this article. And, no, they were not intentional. =P
Also, two games to keep an eye on for how they might mix driving with RPG elements are Rage and Borderlands.