"In qualifying we did both runs on the soft tyres but I had traffic on my first run which meant I didn't have a clean lap," he added. "On the second run I improved my time but I still had oversteer on the exits of most of the corners and more traffic in both sectors one and two which basically ruined that lap."
Things were scarcely any better for van der Garde, who will now start on the back row alongside special guest star Webber.
"After two productive sessions yesterday I just couldn't get the same feeling from the car in FP3 and that carried over into qualifying," admitted the Dutch driver. "Like Charles, I've had quite a few small problems in each session and together they've held us back quite a bit.
"We're struggling to understand the tyre behaviour here and when the track temps went up today it was like having to start again with our understanding of how to get them working," he explained. "My final position in qualie is obviously disappointing, particularly as I made a mistake in turn two on my second run, pushing too hard into the corner and that cost me about four tenths.
"But now we have to focus on tomorrow's race," he added, "and aim for the same sort of performance we put in at the last race in Malaysia," which saw him finish in 15th place after starting from 22nd, getting the better of Chilton over the course of 56 laps at Sepang.
Caterham might not be making it easy for themselves, but maybe they can yet salvage something from Shanghai with a similar performance tomorrow in the Chinese GP.