Like anything worth doing, learning to develop race car setups requires a certain level of commitment.
In the case of GPL, in order to learn how to develop good setups, you need to commit to acquiring a certain level of hardware. This is because without the right hardware, you won't get enough of the feedback from the car that is so essential to discriminating between a change for the better and a change for the worse.
If you haven't already, you also need to acquire a basic understanding of the factors that affect the behavior of all race cars, both real and simulated. Elsewhere in this document is an Introduction to Race Car Vehicle Dynamics, intended to introduce the reader to these factors, as well as a discussion of the specific parameters which GPL allows the race engineer to adjust.
Although GPL can run on a Pentium 166 with a Voodoo 1 card, I do not recommend attempting to develop setups on such a machine.
To run GPL well, I feel that it's essential to get at least 36 frames per second. Due to a peculiarity of its implementation, at anything less than 36 fps, GPL delivers choppy frame flow.
Consistency is the key to accurate evaluation of the effectiveness of setup changes. If GPL is running at less than 36 fps, the delay in delivery of the vital visual information about the car's behavior makes it extremely difficult to drive the car consistently and well.
Also, slower machines introduce more latency in controller inputs, which is a significant problem. Immediate response to control inputs is essential to consistency.
It's possible to get 36 fps with older and slower machines by cutting back on graphics details and sounds. However, this does entail some sacrifice in graphic details, which I feel are important, and the latency introduced in controller responses by slower machines is a serious handicap.
I believe it's very important to use a Force Feedback wheel with GPL. The information which GPL delivers about the car's behavior is crucial to understanding both the setup of the car and the details of the track surface. GPL increases forces with vertical load, and decreases forces as vertical load decreases, and also when the front tires go past their optimum slip angle. The wheel also counter-steers slightly when the rear of the car starts to slide. All this information is crucial to understanding what the car is doing and reacting to it appropriately.
Currently there is only one type of Force Feedback wheel which I feel works well enough with GPL to accurately deliver these subtle but important forces. Unfortunately, this wheel comes with inadequate pedals. For optimal behavior, separate pedals are required as well.
Here are the specifications of the machine which I feel is the minimum optimal hardware for GPL:
Additional details about Force Feedback wheels, and how to set up a Logitech Force Feedback wheel and CH Pedals are available at my Force Feedback page at Eagle Woman's Grand Prix Legends. A fix for a problem with the Voodoo 3 3500 is in the Hardware FAQ.
If you have a second computer available, you can use it to streamline your setup development. It doesn't matter what it is, a laptop or an old 486 will do, as long as you can connect it to your racing computer via a small LAN.
Simply install GRE on the second computer, and share your Setups folder(s) on your racing computer. Now use GRE on the second computer to open setups on the racing computer via the LAN. You can make changes to these setups in GRE, using GRE's extensive features and Help, and save them, and then open them from GPL's Setup menu. This will save the time it would otherwise take to exit out of GPL, make changes in GRE, and then re-enter GPL and load the new or modified setup.
Note that sometimes GPL won't see a new setup or changes in an existing setup made by GRE. In that case, you'll need to switch to a different setup, and then load your new or modified setup.
If you don't already understand the basics of vehicle dynamics, you must acquire this understanding. Even if you are fairly knowledgeable about the subject, I am fairly sure that GPL will teach you new things. It certainly has done so for me!
In GRE Help are two documents, Introduction to Race Car Dynamics and Setup Parameters. The former is an essential read if you don't already have a solid understanding of vehicle dynamics as applied to four-wheeled independently sprung wingless race cars. The latter discusses the parameters available in GPL and makes suggestions for values you can start with.
At a minimum, I strongly recommend that you scan the first document, and I expect you'll refer to the latter fairly frequently if you use this Handbook to assist you in developing setups.
There are also references to several excellent books about vehicle dynamics in the References section. Because GPL's physics model is so detailed and so accurate, virtually everything in these books about setting up cars is applicable to GPL.
There are also links to GPL-specific Web sites in the References section. These sites contain a great deal of information about the particulars of GPL.
If you intend to be a serious student of GPL setup development, and to receive the full benefit of the learning opportunity it presents, I strongly suggest that you read at least Carroll Smith's book and Ricardo Nunnini's Web site. Reading some of the other references would be even better.
The more you learn about the subject, the better!