GPS tracking for cars can definitely be used to track down a cheating spouse and to corroborate any "stories" they try to sell you. GPS tracking technology will make pinpointing your spouses every move in their car - giving you a heads up if they park outside the same apartment complex when they are supposed to be at the bowling alley or at their mother's. There are several types of GPS tracking devices for cars that you can use and each has its own advantages and disadvantages.
Some devices require some level of technical know-how. If you have it, or have access to someone that does (like a friend or a friend's husband), I highly recommend that you get the possible tracker that you can reasonably afford. The best kind take their power supply directly from the car and track tons of information. Less complex devices are easy to install and use, but they suffer from relatively short battery life (5 days on the Zoombak Universal A-GPS Locator).
You can keep track of their activities in real time or go with a device that simply logs the activity - the choice is entirely up to you and your level of suspicion. Either way, you are going to accumulate some sort of history of your cheating spouse of significant other that you are going to want to sift through to find patterns and analyze. Downloading the data and overlay it on the mapping application like Google Maps. Most times you won't even have manually do this because the GPS tracking device you are using is already integrated with Google Maps.
Knowing the position of your spouse's car can give you a better idea if your suspicion about their cheating is reasonable or just life getting the better of you. If the data is there and you see a reoccurring pattern in their activity - like making the frequent stops to an unidentified address, frequently attending dances in seedy establishments, or simply not being where they said they would be - your GPS tracking has provided some relevant information for you to think about.
Is GPS tracking for cars going to give you all the answers that you need? Certainly not. Once you have determined that they are engaged in suspicious activity you will have to confront them and make them realize that what they are doing is wrong. GPS is not going to be able to help you to do that.
What you need is a strong support structure around you. Talk to you friends, get help, reach out to those around you. No one should be with someone who will cheat on them - so stand up and confront the person with how their actions are destroying them and hurting your relationship. If you need to, do this with a friend or trusted adviser. Counselors and pastors work well for this if you are in the care of one or simply don't know who else to turn to. Whatever you do get the help that you need to improve your situation.
Cheaters need to be caught. The life that they are living is destructive to both you and to them. GPS tracking for cars can help them get caught.