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Throttle stop testing on a diesel
Today, while I was waiting for the Tesla to arrive for tuft and pressure testing, I did some throttle stop testing in our W212 Mercedes.
Using a Scangage to monitor throttle position, I was able to hold a constant throttle (ie I didn't use a 'stop' as such - it's not too hard to hold a constant throttle once you get used to it.)
On the same test road that I've been using for my Insight, I recorded the following at TPS = 52 (not 52 per cent obviously, but a constant throttle).
Windows closed: 101 km/h
Windows open: 97 km/h
That calculates to an 8 per cent increase in drag - a bit lower than the change with the Insight (12 per cent) and well under the change quoted in Katz (2016) that has it at 16 per cent for a notchback.
I might do a few more tests with weird rear spoilers.
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