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Why does climate control disproportionately impact city vs highway range?

Why does climate control disproportionately impact city vs highway range?

I'm using the range tool at http://www.teslamotors.com/goelectric#range .

There is a much larger mileage cost to using climate control when doing city driving as opposed to highway driving.

Can someone explain why this is?

85kwh battery
Highway speed = 55 MPH
Climate control = on

90 degrees:
Highway -> 284 miles vs 308 miles
City -> 237 miles vs 299 miles

32 degrees:
Highway -> 249 miles vs 287 miles
City -> 211 miles vs 291 miles

gregv64 | 13 février 2013

Climate control is a fixed amount of energy per time. If you're going 55 it's only going to take 5 hours to go 275 mile, so you're talking 5 hours of using the heater/AC. With city driving you're talking about 11 hours of driving to go the same distance, so that's 11 hours of heater/AC use.

schoendp | 13 février 2013

The HVAC uses approximately the same amount of energy regardless of what speed you are going. Because of this, it is a much larger % of the total energy being used when you are going slower (using less energy to actually drive the car) while driving in the city.

JoeSmith | 13 février 2013

Ok, that makes perfect sense.

Does the city mileage assume stop-and-go driving or is it at a constant (lower) speed?

July10Models | 13 février 2013

The slower the worst it gets. All things being equal, the Model S is very efficient in stop and go traffic also in a constant bumper to bumper. Climate control, headlights, wippers, radio, heated seats is a heavy penalty on range when you are not moving. At about 283.3Watts/mi the car travels 300 miles. Anything more reduces your range. At 400Watts/mi like I drive my range is closer to 212.

JoeSmith | 13 février 2013

Just trying to get a sense for the stop-and-go penalty due to (regenerative) braking loss without considering other electrical drains.

What would you say the percentage mileage penalty is for stop-and-go versus constant speed at city driving speeds?

gregv64 | 13 février 2013

The city mileage definitely assumes stop and go driving. A constant lower speed is the ideal driving condition, and you can get 400 miles driving a constant 30 mph. Normal city mileage is slightly less than highway mileage even without climate control because of the stop and go.

July10Models | 13 février 2013

Let say you don't have anything else on because it is a perfect spring afternoon, same. Providing you are not burning rubber each time you step on the accelerator. I drive through NYC during rush hour every evening. Use very little juice to cross the city because of the slow moving traffic which is sometimes stop and go.