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Comment by nimbius | Hacker News Reader

Speaking as a professional engine mechanic for a chain of Midwest shops, you have no idea how big a ripoff uber and lyft are until you're in the shop.

The rates you make do not cover fleet style usage of your personal vehicle. Cabbies love the crown Vic because its intercooler let's it idle for hours on end with no worries. And they love the Prius because the idle uses no fuel. But your car? Get ready for more oil changes and brake jobs, and a lot more air filter and steering fluid changes as you go around the blocks. The worst I'd charged shop rate was for a Toyota Camry that had $2500 in service because the uber guy was trying to make it last between paychecks that weren't being paid by uber. A month later in august he lost the transmission at 65000 miles because he never idled in neutral.

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Does one need to idle in neural even on automatic gear cars?

In many, if not all automatic transmissions the pump does not circulate transmission fluid when in Park, even though the torque converter is generating heat. It's very possible to overheat a transmission in Park.

He was probably slipping the clutch.

I think you'll find it's been years if not decades since there was a Camry available with a manual transmission

And that would just wear a bearing/spring system or the clutch, which are all repairs that are far cheaper than the cost of an automatic transmission replacement.

But idling an automatic shouldn’t be a problem. It’s a fluid turbine.

Well, that's why tons of Uber drivers use Priuses. It can work out for some people. You don't see them in your shop because it is working for them.

Another instance of survivorship bias with an interestingly backwards definition of “survivor” in this scenario.

>lots the transmission at 65000 miles

That's insane... What's better for wear on the engine, turning it off then on or idling in neutral?

Well for the engine, of course idling

If that's true for newer cars then how come they turn off the engine at the stop lights to save fuel?

Corporate average fuel economy regulations [1] set targets for the average fuel efficiency of all the vehicles a manufacturer sells. Since SUVs are popular and higher margin, car companies often have to do tricks like the auto-off engines to offset poor fuel economies in more profitable segments. Manufacturers that want to go over the limits have to pay a penalty or buy credits from their competitors who go under the limit.

Cars with auto-off also have newer technology made specifically to handle the extra stress like self-lubricating bearings and starters rated for >500k starts.

[1] https://en.wikipedia.org/wiki/Corporate_average_fuel_economy

Does that make a meaningful mileage difference or is it just a marketing trick because it’s so obvious to the user when the engine shuts off that “it must be saving fuel”.

During a normal 15 minute drive, the engine auto shutdown shaves maybe 20 seconds of runtime for me (smaller city without long lights) and it’s at the lowest engine consumption level (idle).

Given that an engine can idle for approx an hour on a gallon, I fail to see how an idle-off makes any meaningful difference for the average driver. It reeks of a marketing scam.

Read the person you are replying to. It doesn't matter if it is useless in real world. What matters is if it beats the tests created by govt bureaucrats.

>stop/start is estimated to boost fuel economy by 4 to 5 percent using the EPA test cycle

https://www.caranddriver.com/news/a19561461/automakers-incre...

It's not useless: a reduction in 4-5% of emissions in urban stop and go traffic would be huge for air quality and health. It likely won't do much if anything for total CO2 output but offloading the emissions to manufacturing of parts needed for extra maintenance (aka a far more efficient power plant in a less densely populated area) instead of driving can still be a net win.

Regardless, fuel efficiency standards have driven a significant amount of innovation even if this specific rule seems absurd from the outside.

Tests vs real world...

They should only do that after they have reached operational temperature. Turning off the engine while it's still cold (i.e. below operational temperature) wears a lot on it. This is why diesel is a bad choice, if your regular trips are short.

Because it saves fuel/emissions?

Idle stop always makes me wince. :S

No intercooler on a crown vic unless you've turbocharged it. They are reliable because they are simple.

That could just be a translation or terminology issue. I've seen folks substitute "intercooler" for radiator, transmission cooler, oil cooler, etc.

My guess here is oil cooler.

meanwhile the guy who's perfectly fine driving for uber is eating cheetos at time and you will never meet him.

it's like being a doctor and complaining that everybody is sick.

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