Appreciate your insights and clarifications.
I am not going to argue drag and coefficients with an aerospace engineer.
Let me ask a few clarification questions:
i) my understanding of the 5-cycle EPA test, done on a dynamometer in a room, the RAW DATA does not comprehend speed/air-drag per se. However, the vehicle manufacturer is supposed to apply certain correction factors to account for these factors. Is that true or not true? If true, are these "fudge factors" or approved by a neutral party?
ii) can you enlighten us on the physical underpinning of a "break-in" period?
Vehicle dynamometer testing does consider speed/air-drag.
Think of a vehicle dynamometer as a resistance training type of machine. The cars driving wheels do not spin freely, but a turning a huge roller which applies a resistive force. The dynamometer has to be set with a supplied set of coefficients to provide a resistant such that the energy/power being expended by the vehicle is equivalent to what would be required driving down the road a the same speed. That's where these coefficients used to set the dyno resistance are determined for the specific vehicle from a series of real vehicle driving tests, typically referred to as coast down tests. There is then a procedure when the vehicle is put on the dyno to calibrate the system to document that the correct speed/vehicle load characteristic is being achieved.
These coefficients, known as A/B/C coefficients are unique for a specific vehicle, so those for a Lucid Air are different from a Gravity which are different from say a Ford F-250 HD pick-up.
So the raw data from each driving cycle, whether energy consumed for an EV or fuel burned for an ICE, are already taking into account the vehicle speed driven instantaneously through the drive cycle, which the load on the vehicle instantaneously varying throughout the drive cycle, including periods of regenerative braking or coasting during the coast-down or stopping portions of the drive cycles. The test cycles are actually performed with a human driver "driving" the route. The operator has a computer display, typically right beside the driver side window which shows a live graph of vehicle speed against the prescribed profile. There are specified tolerance bands where the operator needs to keep the current speed inside the target. Not all drivers drive exactly the same. I've experienced some drivers which where much "smoother" versus some who tended much more to a binary accelerator control (full WOT or zero throttle/brakes). Provided they stay within the defined tolerance bands, all are consider legal drive cycles.
While much of this testing is done by the manufacturer, the regulatory agencies have the right and will perform some amount of confirmatory tests. In these cases the manufacturer is required to provide the test vehicle to the agency who then tests it per the regulation in their facility. If the results do not match the manufacturers, lets just say there will be a period of "discussion" that takes place. Ultimately the regulatory agency can reject and not approve the manufacturers. I've been a part of such confirmatory tests in the past. Many times they tend to be on new vehicles, first time certifications, or cases where there might be some history or events which could bring the manufacturers data into question. I've seen references in the past that suggest maybe upwards of 15% of tests go through a confirmatory test phase, but do not have first had knowledge to say if this is accurate or whether the level may have changed over the past few years given some of the current political environment around agencies like EPA.
The concept of break in testing comes from from basics of fact that for a brand new vehicle/engine, you need to run it for some amount of time before things like piston rings, bearings, gears sets, would "wear in" or "break in". This helps stabilize test results for things like fuel burn/energy consumed and engine emissions production. The work between regulators (EPA, ARB) and industry to decide appropriate test procedures and duration were outside of my personal professional involvement, but for ICE vehicles 4,000 miles ended up being the generally accepted period which is what I always found to be used. Now for EVs I've found some references to suggest that 2,000 miles seems to be more what is now generally accepted. This break in period is for the whole vehicle as a system, so for an EV, means both the car and battery are new and run together for that 2,000 mile period. I've done some quick searching to see if I can find if there's a single defined drive cycle for that, but without digging really deep in SAE and EPA/ARB procedures, haven't come across what I feel is a reference I'm willing to quote.
If you want to do a little investigation, this seems like an quick read. It has some links which I think will take you to references showing the actual drive cycles.
EPA's National Vehicle and Fuel Emissions Laboratory (NVFEL) tests new cars and trucks sold in the U.S. to ensure that they comply with federal emissions and fuel economy standards.
www.epa.gov
I will warn you, the regulations and much of the technical documents can seem like they are written in a foreign language. Trying to wade through them is not for the faint of heart. Even for someone like myself that worked in parts of this area for about 10 years during my professional career, it takes quite a bit of concerted effort to wade my way through them, typically multiple references deep, before I start to get what I think is a basic understanding.
