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Old 12-31-2020, 01:12 AM   #1 (permalink)
JulianEdgar
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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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