With the reversing bits, that's more like gymkhana than autocross, but that's the basic idea, anyway.
For a long time I've thought that GT4 should just include the basic racing game like GT3 minus the rally section. Then they should use the car models to do specialty versions: GT4 Rally, GT4 Drag, GT4 Drift, GT4 Autocross, etc. for cheaper prices. That way they could get the competition formats correct for each sub version, since the main development was already paid for by GT4. And I would never be required to drift or drag race, but people who wanted to could, without having to rally or autocross.