- Apr 21, 2020
- Reaction score
- San Diego, CA
- Ford F-150 SuperCrew Cab, Tesla Model 3P
If the test team does it consistently, yes. That isn’t a guarantee.So it is a constant for each vehicle? Thanks good point.
Setting ambient temperature is trivial. Characterizing drag is not. With CFD is easier than in the past, but if two parties are building the model, two sets of results aren’t unlikely.
Within the EPA or within a make, results are probably consistent. But if Ford built a model for a BMW, and if Toyota built a model for a Ferrari, there is a good chance BMW and Ferrari would disagree to some degree.
EPA ratings come from the OEM. EPA verifies a small percentage of them, but if they've published what they consider to be an acceptable deviation from their own results, I haven't found it.
My point isn't that the test is flawed. The test is fine, it just has a margin for error in dyno load.
It could be better if they actually ran the vehicles around a track at standard ambient conditions so that drag was actual, not calculated and then converted into the load on the dyno, after which the results go through one of several acceptable 'real world' fudge factors.