Autocross side-by-side
 

Personally I find these a ton of fun to watch. My friend vs me.
inb4 no turbo no care

It's also nice to do the same thing with data. Even a simple MPH versus distance traveled trace is very revealing. Most often, the key to course time for a given car comes down to just two places out there. So for instance if a decent first year autocrosser showing promise shares his car with a hot shoe on his game there will be many areas on the course where there is NO real difference. So for the new guy to find time, he must study the few places real time WAS found. And then determine how this was done so that he can try to do the same thing. This is easy to do if you use time-slip plots showing the Wheres followed by examining other data to determine the How & Why of it. In your videos you can clearly see the dead even aspect in many zones.

I have seen that much of autocross comes down to carrying speed through tricky elements combined with earlier power down initiation. So when you feel like tapping the brakes…don't...keep it floored or possibly hold speed with a steady but reduced gas pedal. The fastest guys never lift all the way for more than an occasional tenth of a second or two the whole run including during braking where they might come back to 25-30% throttle. The other thing is good car positioning and early steering inputs. If you are "late" on a slalom entry it will mess up all the following gates. So do whatever is needed to start a slalom properly (which can feel slower) and it will find you time a few gates in. Those are some of the basic concepts.

data is a bit more difficult to acquire, video is e-z mode!
Usually he beats me by about a second so 0.5 seconds is a huge improvement for me.

The way I look at it, video IS data. It's just not very processable to pull out certain things. If we were at the same event I'd just log your car and have some fasties do the same…then show you where the speed is to be found and what you should do differently on your next run. I've sped up countless people out there! And some were already quite accomplished.

what tools do you use?

I use various dataloggers. My favorites are the www.Race-Technology.com pieces.

If you have a smart phone, you can download apps that can start to give you a taste of the concept. There are decent ones for both Android phones and Apple iPhone/iPod Touch devices.