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in the past automatics tended to have fewer gears, making them less efficient by default. but modern autos are now more efficient than even a perfect driver of
by modzu 8y ago
in the past automatics tended to have fewer gears, making them less efficient by default. but modern autos are now more efficient than even a perfect driver of a manual
- analog31 8y agoIndeed, and as I understand it, there's a mechanism in a modern transmission that disables the torque converter when cruising, further improving efficiency. Over the course of my life, I've noticed a remarkable improvement in the behavior of automatic transmissions, going from "jerky" to "smooth" for lack of better terms. While overseas last year, I drove a large Mercedes van that even sensed when I was descending a hill, and downshifted the way I would have done it in a stick shift car.
- crushcrashcrush 8y agoCorrect, many modern automatics are “full lockup” like the ZF8.
- davidzweig 8y agoMy 25 year old diesel automatic Toyota Estima people carrier has a lock-up clutch that engages at about 75 kph. It's possible to modify the wiring to engage it at lower speeds, or manually select gears.
- perl4ever 8y agoYes, but I find modern automatics to be frustrating in their shift points. I have a 30 year old manual transmission sports car, with probably less than 140 hp, but because of the gearing, driving is pretty much all done between 2500-3000 rpm, and it feels reasonably responsive. I also have a 6 year old SUV, with an automatic that has a lot of gears, and a turbo engine with a lot of power, but it feels underpowered much of the time, because if you are just cruising it will end up at about 1200-1500 rpm and seem as though it is practically lugging the engine. If it was just programmed to stay a little higher, like 2000-2500, it would feel as powerful as it is. There is of course a "sport mode", but it is too aggressive. Also, modern automatics tend to change their behavior all the time according to mood. There is nothing more counterproductive than an "adaptive" transmission (or other system). The word "adaptive" simply means that it isn't responsive when you do something different. Which is bad.
- modzu 8y agosure, but there is a tradeoff between performance and fuel efficiency: your sports car crusing along at 3000rpm is sucking fuel to do it. i think being programmed for efficiency is a reasonable default, and sport mode available when you need/want it. of course soon enough any differences in ICE transmissions will be moot..
- perl4ever 8y agoExcept it isn't. You'd think that 30 year old engine technology, combined with double the rpm would use hugely more fuel, but in practice it's not that big of a difference. What has changed is that manufacturers have figured out that nobody makes a buying decision on the nonquantifiable driving characteristics that auto magazines used to describe, and therefore it's a no-brainer to sacrifice them for 1 or 2 mpg more. And of course, the newer SUV gets much worse mileage anyway. If a couple mpg really matters that much to you, you can always drive less too. The earth doesn't care if you get twice the mileage or drive half as much.
- RickJWagner 8y agoYes, and automatics are now noticeably faster. It makes me a little sad, though.
- sokoloff 8y agoDouble manual transmissions with computer controlled (often wet) clutches are the current fastest trans. They don’t have a left pedal, but they’re mechanically more like a manual trans than a traditional automatic.