Forza Motorsport 2 Car Upgrades Explained
Q: One of the most obvious questions on the minds of those anticipating Forza Motorsport 2 is how car upgrades is going to work this time around. So from a top level design perspective, what’s changed about the upgrades system – if anything?
Dan Greenawalt: One of the changes in the upgrade system isn’t an upgrade at all. As we’ve discussed in previous reports, we’ve added more granularity to the car classification system. Each car and upgrade now gets a Performance Index number – based on a non-linear math model created by neural-network AI search. This Performance Index (PI) makes upgrading more of a game in-and-of itself. For example, let’s say you’ve got a Corvette Z06 that you want to optimize for Class A. Your Corvette starts at a PI 687 and Class A cuts off at 750. There are several upgrades that will get you up to 750. You could emphasize grip with ride height, tire compound, aero, weight; or you could go for power. Truthfully, you should go for a balance. Achieving that balance is where the PI system really helps. PI allows you to mirco-manage how many PI points each different upgrade gives you. By the way, these numbers are not finalJ. We’re still fine-tuning and balancing the final numbers.
Q: Sounds like the granularity gives players a finer game of resource management and allocation. What else have you guys added to the car upgrades system?
DG: We’ve also added several new upgrade types, especially in the engine area. For example, we’ve split out engine block upgrades and top half upgrades. Engine block upgrades increase the engine durability, decrease its inertia and provide mild power increases, while cam and valve upgrades raise the redline, radically change the audio and skew the engine curve toward high RPM horsepower.
Q: Tire physics plays an important role in the overall Forza Motorsport 2 simulation – what kind of upgrade improvements have been done to car tires?
DG: Like the engine upgrades, the tire upgrades have been completely over-hauled to give you more choices. For example, now you have the opportunity to choose from different tire manufacturers, not just different compounds. Each of the different manufacturers have different characteristics such as grip (coefficient of friction), responsiveness (peak slip angle) as well as heat and wear characteristics. In playing the game so far, I’ve found that all of these new choices in combination with the new PI system have really changed my upgrade strategy. For example, I rarely chose the tire with the most friction. I usually look for a combination of price and responsiveness while choosing a manufacturer compound that doesn’t bump my car class. Of course, I also take my favorite brand into account as well.
Q: Were there any upgrade improvements you guys could only do on Xbox 360 as opposed to Forza Motorsport on Xbox?
DG: With the added power of the Xbox 360, we’ve improved weight and inertia representation in the cars sub-systems. We track weight and inertia for clutch, tranny, crank, driveline, flywheel as well as wheel widths, rim model and rim size. Again, this weight and inertia factor plays heavily into my upgrade strategy. My upgrade strategy is to lose unsprung weight first, powertrain weight/inertia second and body weight reduction last. Just like in the real world, where you lose the weight has a big effect on your lap times. Sure, there is more weight to lose in the body, but if you’re optimizing the car for a class, this is the stealth way to do it.
Q: And of course we can still do engine swaps…
DG: Yes. In the original Forza Motorsport, players could engine swap within a given manufacturer. For example, you could drop a Skyline engine into the Silvia. For "Like" damage and customization, this was no small licensing feat. So what’s new here for Forza 2? Well, we’ve added roughly 100 more engine swaps for even more cars. That’s cool, but by far the coolest new upgrade is the powertrain swap. Yup, that’s right. Now, you can not only swap out the powerplant, you can even put in a new drivetrain. For example, ever want to put an AWD Lancer EVO drivetrain into a FWD Eclipse? Now you can – only in Forza Motorsport 2 of course!
Q: So wait, back to your AWD Eclipse for a moment – what would a powertrain swap like that do to the car’s PI number?
DG: It depends on the characteristics of the swap. For example, if you’ve already upgraded your Eclipse engine, the Lancer engine may actually have less power – plus, the AWD Lancer drive-type is heavier. As a result, the PI would drop. However, the AWD drive-type has different driving characteristics. Also, the Lancer engine has tons of upgrade potential.
Q: What about the upgrade parts manufacturers this time around? Can you talk about some of the new brands and how all of this fits into the single-player career?
DG: In Forza Motorsport 2, not only can you level your driver profile, you can also level your car. As your car levels, you unlock discounts on different aftermarket manufacturer brands. For example, leveling up a Porsche will unlock discounts on Pirelli tires in the upgrade area for all cars. Similarly, leveling Mazda cars unlocks discounts on Greddy Fuel Systems. Greddy fuels System upgrades can be used on various Mazda, Mitsubishi, Nissan, and Toyota models. Different car brands unlock different parts brands. It’s a giant, massive, patchwork and we've got a ton of new licensed brands in there this time. There quite a bit of strategy to leveling different cars in order to get the best discounts. It’s a pretty addictive system.
Q: Sounds like the upgrades system overall is getting a big shot in the arm. At the end of the day, what did you hope to accomplish as a game designer by revamping the car upgrades and Car Class/PI system?
DG: Car Classification missed the mark in the first version. It was better than anything I’ve seen in any other game with upgrade, but there were still a small group of cars that could dominate. Testing thus far indicates that we’ve significantly affected that issue with the non-linear PI system. We also have a backup plan built in – just in case something goes awry after ship. Regarding the upgrades area itself, I see upgrades area as a game within the game. It’s a place where some players can learn more about cars, technology and brands. It’s a great sandbox for experimentation. It will definitely stoke good community debate and fuel passion. More than anything, I’m excited about the new level of risk/reward and strategy that is now built into the upgrades game. These new features in the upgrades and the career take us one step closer to the game I see in my head, but there is always more to do.
