Comment by 6gvONxR4sf7o
4 days ago
Same here. Waymo doesn’t make me feel car sick, while aggressiveness-incentivized uber/lyft drivers do.
Thinking of incentives, I wonder what happens when self driving is “solved” to the point they can start nickel and dime optimizing. I wonder if waymo starts driving overly aggressively at that point too.
A dime of commercially priced electricity is around a kWh depending on where you are. That'll take a car a lot further than you think, and the more aggressively you drive the more electricity gets used. The most efficient way to drive is the flattest, most leisurely route.
The only way aggressive driving becomes profitable is when you've exhausted your supply of cars. Even then, it's not clear to me that you'd increase profit in that time by driving faster, since one car over the course of a day might squeeze in one or two extra rides at most. Just having more cars that sit idle until needed would accomplish the same thing with no extra risk.
In fact, the biggest area for optimization is getting the car to the next rider from the end of a previous ride. But that's not about being fast, that's about positioning idle cars in the right places to minimize distance to potential riders. If pickup distance becomes a hard bottleneck, it's again about capacity, not speed. Most of the between-trip driving is not on highways and back roads, it's through dense areas with lots of stop signs and traffic lights, so increasing speed isn't even really feasible.
If aggressive driving is 5% faster, then your expensive investment (the cars and the business) might get a few percent better utilisation (assuming liabilities don't increase much). More likely to see aggressive driving on way to pickup?
Capital costs matter, and how quickly you get ROI matters.
5% higher velocity doesn't mean arriving at your destination 5% sooner. A car traveling 52.5mph will complete a trip (absent acceleration/deceleration/stops) of 3 miles only about 10 seconds faster than a car traveling 50mph. That's the upper bound, because cars have to stop. The speed is not the efficiency bottleneck, not by a long shot.
Even if you saved thirty seconds on each ride throughout a day, that doesn't translate to more profit. It translates to the ability to take on extra rides. Which in total, is maybe one or two. You're talking about an extra $30 or so in revenue. Subtract off normal overhead and you're looking at maybe ten dollars of extra profit per vehicle per day at best.
You're also assuming the service runs at capacity at all times. You will infrequently be at capacity. Arriving ten seconds sooner doesn't matter if you just have another car you can dispatch for another rider, and optimizing how and when to bring cars in and out of service becomes the bottleneck.
There are so many inefficient aspects of a naively designed ride sharing service that can be optimized for real meaningful profit. And almost all of those things can be done without changing the way the car handles in any way. Just making sure you have vehicles in the right places at the right times, or fueling vehicles at more opportune times, or choosing more optimal pickup and drop-off locations could increase the number of rides you can perform, which is what translates into profit.
Because of how many miles taxis drive their depreciation as a physical asset that wears out costs more than the interest on the money invested in them. To the extent that driving aggressively generates more wear or introduces more accidents it will likely end up costing more money.
1 reply →
Taxis charge time + distance, not flat fares. Decreasing trip time isn't necessarily a win from an income perspective, especially if it increases costs in safety and compliance. The real balancing force is customer frustration. Long trips are one of the primary complaints in robotaxi services.
Electric engines are very efficient; aerodynamic drag is by far the biggest source of efficiency loss. The most efficient traversal for a fixed time interval is fast acceleration / deceleration with a reduced top speed. OTOH the most efficient for same time interval for a gas vehicle would be a slightly higher top speed but lower acceleration / deceleration.
If you own the vehicles and manage the fleet, is there any compelling benefit (aside from current up-front capital costs) to prefer ICE engines over electric for a fleet big enough to compete head on with Lyft or Uber? Even the additional uptime per vehicle thanks to lower ongoing maintenance is a compelling enough reason to jump for EVs.
1 reply →
> aerodynamic drag is by far the biggest source of efficiency loss.
Rolling resistance is a bigger source of loss under 30 mph.
> The most efficient traversal for a fixed time interval is fast acceleration / deceleration with a reduced top speed
Wouldn't it be increasing speed for half the trip and decreasing it for the other half?
Why would fast acceleration and deceleration be more efficient? When you drive an electric car it’s usually the opposite: fast acceleration drains the battery fast, and slow deceleration allows for better regenerative braking without having to use the actual brakes.
3 replies →
If history can teach us something it is that they will.