Road Trip Experience + Roof Cargo Box Efficiency

[dogmodes]

I like data as much as the next guy, but I'm gonna come out and just say it: there's absolutely no way that at a -14% range hit is representative of the energy consumption penalty with a roof-top cargo box. I had a 11 cu-ft Thule cargo box (which has a smaller cross-sectional area as yours) that I road tripped with a handful of times with my model 3 2018 RWD and only on my best days would I get around 300 Wh/mi, especially at fast highway speeds. I can't recall the consumption exactly, but I remember my roadtrip from SF to SD (1,000 mi) and back probably averaged somewhere between 375-400 Wh/mi. We were fully loaded with 5 people and their stuff. It was in September, so wind resistance was at its most kind. I remember the efficiency was absolutely terrible because everyone in the car became miserable by the end of the trip. We stopped so often for charging, and it didn't help that some charging stops lack real amenities. If you have any significant headwinds with a rooftop cargo box, the efficiency drops sooo much.

I wouldn’t discount the weight in the car. I have the same box and if it’s empty and normal driving it doesn’t add very much but some wind noise, maybe 10-15%. If the car is loaded for a trip I definitely notice the hit.

 

[BagheeraNY]

Although this isn't very precise because the road trip started halfway through the month, we completed a ~7700 mile road trip across the county with a rooftop cargo carrier this summer. My monthly counter for Wh/mi before the trip was 247 Wh/mi and for the month of the trip was 313 Wh/mi. Definitely some mountain passes / significant elevation changes in those numbers.