An integrated circuit, in accordance with one embodiment of the present invention, includes a first device under test module coupled to a first ring oscillator module and a second DUT module coupled to a second ring oscillator module. A variable gain feedback system generates a feedback signal for combination with the digital input, thereby to provide offset cancellation. The forward roof element may be pivoted relative to the rearward roof element about a first axis that is perpendicular to the vehicle longitudinal plane.