7 ms·

Why all this focus on weight? Regenerative breaking makes weight 80% more irrelevant, or did I miss something?

speedgoose 7y ago
It's still good to be light on low speed corners. At high speed the aerodynamic down force is much greater. I think they just want to have a super fast car for a few people, and to do so you need to pollute with an ICE engine.
deleted 7y ago
[deleted]
ska 7y ago
This is a performance car company. Weight is 100% relevant, it will help with acceleration and deceleration performance, cornering especially at speeds low enough that down force isn't determining your grip, and general responsiveness.
dragontamer 7y ago
Road wear is IIRC to the 4th power of weight. That is to say, a 4500 lb Tesla Model S has 5x the road-wear of a 3000lb Toyota Camry. If all Tesla Model S drivers were willing to pay 500% the road-taxes to make up for their 5x damages that their cars do to our roads, I think I'll be cool with them using their road-destroying heavy batteries. And the F150 drivers too, while we're at it.
- djrogers 7y ago
  A Model 3 starts at 3,550lbs, vs 3,241 for a Camry. A model S is not in the same class as a Camry, so comparing them is not useful. A better comparison- a Mercedes S Class, starts at 4,500lbs to the 4,800lbs of a Tesla Model S. In both cases there’s a mere 300lb difference (less than 10%), which is way under the 1500lbs/ 50% difference your argument is based on.
- zaroth 7y ago
  You are generally correct that a 4,500lb car will do 5x the road wear per mile than a 3,000lb vehicle. (Although some studies find damage increases closer to a power of 3 not 4). However it’s extremely important to ask... 5 times what number? The cost per mile in terms of road damage is mainly a function of axle weight and designed load and volume of the road surface. The damage per mile per ESAL (Equivalent Single Axle Load) can vary from $0.03/ESAL-mile to $5.90/ESAL-mile when you exceed the design load of the road. Low volume roads will have a higher ESAL because of natural wear exceeding use-based wear. Since passenger cars will never exceed the design load of a road, this is not a factor in our analysis (but it’s a very big deal for heavy trucks, particularly on rural roads). Since low volume road wear is predominantly due to natural causes and not road-use we should probably exclude those as well. Just to put this in perspective, the cost per mile per ESAL of $0.09 (a relatively high volume road that operates within vehicle weight design spec), gives us road damage for a light passenger car (3,000 pounds) or 0.0002 ESAL which equates to $1.80 per 100,000 miles. Increasing to an ESAL of 0.001 results in a wear cost of $9.00 per 100,000 miles. Basically all road wear comes from heavy trucks with an ESAL > 1. This is compounded when those trucks exceed the design load of the road, which can add another up to 500x multiplier on the damage per mile driven. The damage/road wear cost for passenger vehicles is a barely even a rounding error by comparison. Based on this simple analysis, I do not believe it is at all justified to claim that Teslas (or EVs in general) have “road-destroying heavy batteries.” [1] - https://pavementinteractive.org/reference-desk/design/design-parameters/equivalent-single-axle-load/ https://pavementinteractive.org/reference-desk/design/design... [2] - https://www.fhwa.dot.gov/reports/tswstudy/TSWwp3.pdf https://www.fhwa.dot.gov/reports/tswstudy/TSWwp3.pdf
  - ska 7y ago
    This is true. The real problem is trucking, and the way roads are paid for it amounts to a massive public subsidy to that industry, with lots of market distortion around that (see also, state of US rail systems).
    - zaroth 7y ago
      In the sense that passenger cars aren’t causing really any wear and tear to our major roadways, this is absolutely true. However, the value of having those major highways is still extremely high to passenger cars and trucks alike. I benefit greatly from well maintained roads, even if my use of those roads is not damaging the road basically at all. So you need a weighted analysis of use and value as well as wear & tear to come up with a “fair” allocation of costs. Even people who don’t own a car benefit greatly from those roads, due to their logistical necessity for everyday life, not to mention mail and package delivery to their homes. To the extent that passenger car drivers overpay for their commensurate road wear & tear, car owners are subsidizing non-car-owners because the goods they buy are cheaper than they would be if they had to pay for the true fully loaded logistics cost. You could charge the trucking companies more. Then prices of transported goods would just increase to compensate and we’d all be roughly back in the same place maybe? Non-car owners would be worse off. To the extent that roads are being subsidized more than rail then this would distort the market and limit freight volumes. I have a feeling that the markets are not tremendously out of balance, and that it’s not like we’re sitting on massive unused rail freight capacity that just can’t operate profitably because roads aren’t expensive enough? But that’s a whole different topic.
manigandham 7y ago
It's a limited-run hypercar capable of 250mph+. Weight makes a massive difference in performance and effiency.

It's still good to be light on low speed corners. At high speed the aerodynamic down force is much greater. I think they just want to have a super fast car for a few people, and to do so you need to pollute with an ICE engine.

deleted 7y ago

[deleted]

ska 7y ago

This is a performance car company. Weight is 100% relevant, it will help with acceleration and deceleration performance, cornering especially at speeds low enough that down force isn't determining your grip, and general responsiveness.

dragontamer 7y ago

Road wear is IIRC to the 4th power of weight. That is to say, a 4500 lb Tesla Model S has 5x the road-wear of a 3000lb Toyota Camry. If all Tesla Model S drivers were willing to pay 500% the road-taxes to make up for their 5x damages that their cars do to our roads, I think I'll be cool with them using their road-destroying heavy batteries. And the F150 drivers too, while we're at it.

djrogers 7y ago
A Model 3 starts at 3,550lbs, vs 3,241 for a Camry. A model S is not in the same class as a Camry, so comparing them is not useful. A better comparison- a Mercedes S Class, starts at 4,500lbs to the 4,800lbs of a Tesla Model S. In both cases there’s a mere 300lb difference (less than 10%), which is way under the 1500lbs/ 50% difference your argument is based on.
zaroth 7y ago
You are generally correct that a 4,500lb car will do 5x the road wear per mile than a 3,000lb vehicle. (Although some studies find damage increases closer to a power of 3 not 4). However it’s extremely important to ask... 5 times what number? The cost per mile in terms of road damage is mainly a function of axle weight and designed load and volume of the road surface. The damage per mile per ESAL (Equivalent Single Axle Load) can vary from $0.03/ESAL-mile to $5.90/ESAL-mile when you exceed the design load of the road. Low volume roads will have a higher ESAL because of natural wear exceeding use-based wear. Since passenger cars will never exceed the design load of a road, this is not a factor in our analysis (but it’s a very big deal for heavy trucks, particularly on rural roads). Since low volume road wear is predominantly due to natural causes and not road-use we should probably exclude those as well. Just to put this in perspective, the cost per mile per ESAL of $0.09 (a relatively high volume road that operates within vehicle weight design spec), gives us road damage for a light passenger car (3,000 pounds) or 0.0002 ESAL which equates to $1.80 per 100,000 miles. Increasing to an ESAL of 0.001 results in a wear cost of $9.00 per 100,000 miles. Basically all road wear comes from heavy trucks with an ESAL > 1. This is compounded when those trucks exceed the design load of the road, which can add another up to 500x multiplier on the damage per mile driven. The damage/road wear cost for passenger vehicles is a barely even a rounding error by comparison. Based on this simple analysis, I do not believe it is at all justified to claim that Teslas (or EVs in general) have “road-destroying heavy batteries.” [1] - https://pavementinteractive.org/reference-desk/design/design-parameters/equivalent-single-axle-load/ https://pavementinteractive.org/reference-desk/design/design... [2] - https://www.fhwa.dot.gov/reports/tswstudy/TSWwp3.pdf https://www.fhwa.dot.gov/reports/tswstudy/TSWwp3.pdf
- ska 7y ago
  This is true. The real problem is trucking, and the way roads are paid for it amounts to a massive public subsidy to that industry, with lots of market distortion around that (see also, state of US rail systems).
  - zaroth 7y ago
    In the sense that passenger cars aren’t causing really any wear and tear to our major roadways, this is absolutely true. However, the value of having those major highways is still extremely high to passenger cars and trucks alike. I benefit greatly from well maintained roads, even if my use of those roads is not damaging the road basically at all. So you need a weighted analysis of use and value as well as wear & tear to come up with a “fair” allocation of costs. Even people who don’t own a car benefit greatly from those roads, due to their logistical necessity for everyday life, not to mention mail and package delivery to their homes. To the extent that passenger car drivers overpay for their commensurate road wear & tear, car owners are subsidizing non-car-owners because the goods they buy are cheaper than they would be if they had to pay for the true fully loaded logistics cost. You could charge the trucking companies more. Then prices of transported goods would just increase to compensate and we’d all be roughly back in the same place maybe? Non-car owners would be worse off. To the extent that roads are being subsidized more than rail then this would distort the market and limit freight volumes. I have a feeling that the markets are not tremendously out of balance, and that it’s not like we’re sitting on massive unused rail freight capacity that just can’t operate profitably because roads aren’t expensive enough? But that’s a whole different topic.

manigandham 7y ago

It's a limited-run hypercar capable of 250mph+. Weight makes a massive difference in performance and effiency.