I decided to see what I could do for a reasonable price using tools I already own or that were inexpensive. The traqmate stuff that GRM published is awesome, but I have other car budget items with higher priority. And the quality of tools seems to be increasing rapidly due to the growth in power and ubiquitous presence of smartphones.
data collection: iphone 3gs
data collection: PLX kiwi wifi OBD2 reader
video: gopro hero
IOS data collection app
video overlay tool
external GPS for iPhone
For the data collection app on the iphone, I wanted to be able to export data so that it could be overlayed onto the gopro video, and I wanted it to be able to access the OBDII data from the car. I looked at Harry's Lap Timer and CMS lap timer. I decided to go with Harry's as the export options seemed more straightforward. Also, support for Autocross seemed simpler as well.
Cost: $20 for HLT Pro.
GPS: Bad Elf. This unit offers quick lockon, much better precision than the internal GPS of the phone, and a 10hz update rate. HLT supports it natively.
For video overlay, I looked at Dashvision, RaceRender, and TrackVision. TrackVision had the advantage of having a specific supported export file format from HLT, and seemed very powerful, but was the most expensive by far. Dashvision seemed focused on cyclists of the pedaling variety. Racerender supports multiple input data files, multiple input video files, can do PIP, etc. Also it was the least expensive for the full featured version.
So after a couple of hours fiddling around tonight, here are the results. Criticize my driving if you wish - note several things, please: 1) it's 55 degrees 2) it's wet wet wet 3) I am on four year old RS2's, and they liked heat when they were young, and did I mention it's 55 degrees? Traction was hard to find.
Also, the G Meter is inaccurate due to my not having calibrated the position of the phone in its cradle. HLT has an option to replace all of the recorded acceleromoter data with derived values calculated from the GPS data, but I have not done that yet.
Some time savers for anyone else considering doing this:
* for 10hz GPS update rate, you have to set it 10 hz in the settings for both HLT and the Bad Elf app
* calibrate your phone position in the cradle, so your accelerometer readings are accurate
* OBDII data had some dropouts.
* when defining the autocross course within Harry's Lap Timer, use your first run. The docs say to do it when you're walking the course. I had the set screen time out on me. Perhaps I did something wrong, but setting it using a run worked fine.
* running HLT and the Bad Elf gps dongle simultaneously is a huge power drain.