9 ms·
I suppose the same should apply to hybrid cars, which outnumber pure EVs significantly [1]. The effect comes from converting the kinetic energy back to the batt
by nine_k 1y ago
I suppose the same should apply to hybrid cars, which outnumber pure EVs significantly [1]. The effect comes from converting the kinetic energy back to the battery charge via generation instead of wasting it via friction, which is the whole point of hybrids.
[1]: https://www.consumeraffairs.com/automotive/how-many-electric-cars-are-in-the-us.html https://www.consumeraffairs.com/automotive/how-many-electric...
- frollogaston 1y agoAnd manual transmission cars kinda, though the energy is still wasted of course
- OptionOfT 1y agoDepends on how you drive. I never engine braked on my manual. Brakes are easy to replace. Clutches are not.
- eptcyka 1y agoYou need not burn your clutch to engine break.
- hassaanr 1y agoengine braking does not have any effect on the clutch, other than while downshifting, which if you're blipping/rev-matching has practically no effect
- isoprophlex 1y agoExactly, if your clutch suffers abuse when you are shifting gears (unless you're trying to aggressively accelerate of course) you need to rethink what you're doing. Not saying it's smart but when predictably decelerating on the highway I sometimes shift gears by rev matching and changing without even touching the clutch, for the fun of it.
- stouset 1y agoSame on a motorcycle. My current bike has a quickshifter (for both up and down shifting) but even without one you can shift up and down without ever touching the clutch just by pushing on the shift pedal while blipping the throttle off-and-on (for an upshift) or on-and-off (for a downshift). That’s all the quickshifter is really doing anyway, it’s just quicker at it than you are. I’d wager bordering on 100% of my clutch use is when coming to a complete stop.
- MindSpunk 1y agoYou don't engine brake with the clutch, you engine brake by downshifting and using the higher engine RPM in lower gears to brake the car via wasted compression.
- dotancohen 1y agoAnd that downshifting involves a clutch operation, moving the engine into a higher RPM. That most certainly wears down the clutch, talking as someone who's replaced quite a few of them.
- throwawaysoxjje 1y agoAre you really shifting so much that your clutch slip in the middle of the shift effects clutch lifetime?
- beau_g 1y agoI've seen an interesting A-B test with this seeing the difference in clutch wear between the Ferrari F1 transmission in the 599 and 612 and the DuoSelect transmission which is essentially the same box in the Quattroporte. The shifting strategy and technique is more of a controlled variable here because the shifting is automatic though it's a somewhat traditional manual gearbox with hydraulic actuation. The QP is a bit heavier but the Ferraris make a lot more power. From what I saw the cars that fared far worse were the Quattroportes, and those that ate the most clutches by far were the ones putting around the city, especially in San Francisco, Marin, Los Altos Hills, etc. where people are slowly creeping into parking spots on hills. On the Ferraris that are weekend warriors that get driven hard the clutches could go 30k+ miles no problem, Quattroportes would come in with smoked clutches in a few thousand miles sometimes.
- jve 1y agoSorry, ain't native: Which car use downshifting to help braking? Cannot wire in my brains whether this example is pro-downshift braking or not.
- 01100011 1y agoYep, years ago I had a friend with a VW Beetle and he'd never use the brakes unless he had to. I thought it was cool and carried the story with me. One day I mentioned it to a mechanic friend and that was his exact response. I've never changed a clutch, but I've changed plenty of brakes and yeah, not hard or expensive.
- isoprophlex 1y agoYou don't need to touch your clutch to do engine breaking. If you wear out your clutch by shifting gears you're doing something wrong
- michaelcampbell 1y agoYou engine brake every time you lift off the throttle and don't depress the clutch. I know what you mean here of course, but I suspect your driving habits are saving you less than you think.
- cloverich 1y agoSurprisingly you can get nearly same effect in automatics. I put around 60k miles on my first automatic (after120k+ on my first two cars, manual transmissions) and when i got my brakes checked at 63k they noted my brakes were still "brand new". I do gamify reading traffic to try and brake as little as possible (to help pass time etc), but was still surprised how far this takes you given i do plenty of stop and go traffic driving. This was a v6 sedan so lighter than an suv / truck. I expected it to not work in automatics but it does to at least some extent. I swapped for an EV before taking it the usual distance and curious if anyones pushed further and how far.
- MindSpunk 1y agoIt's not "nearly". It's exactly the same effect. Compression braking. Even if you're not on the throttle the engine is still rotating as it's connected to the wheels. If the engine is rotating it is compressing air. If it's compressing air but not igniting fuel (throttle closed) then it will suck energy out of the wheels to compress the air. You can do it in an automatic, you just have to force it to select a lower gear using the gear number options (1, 2, 3, 4) or using the tiptronic mode. The lower gear means the engine will displace more air in the same amount of time, increasing the rate it pulls energy from the wheels. People think you can't do it in automatics because they try very hard to keep engine RPM low where the effect is diminished.
- peterbecich 1y agoRelated to this: https://en.wikipedia.org/wiki/Compression_release_engine_brake?wprov=sfla1 https://en.wikipedia.org/wiki/Compression_release_engine_bra...
- agurk 1y agoIf it takes energy to compress the air in the cylinder - doesn't it also release most of that energy when that compressed air is expanded on the subsequent stroke? If you release the compressed air without pushing the cylinder down you would lose that energy, but you would need a extra device to do so (by lifting a valve at the right time). This option does exist for large vehicles like trucks as a compression release engine brake [0], but this isn't something you'd have on a family car. In a petrol engine you always want the same ratio of petrol to air in the mix that is taken into a cylinder. As you want to vary the amount of fuel, and therefore power developed, you have to be able to therefore limit the amount of air that is sucked in. Otherwise the engine would always run at full power. There is a mechanical restrictor called a throttle plate that lives inside the throttle body that restricts how much air the cylinder can pull in (and therefore how much fuel is injected to get the same fuel/air mix). This is controlled by the throttle. When you are coasting, this plate is in its most closed position. This creates significant resistance on the intake stroke, and is where the majority of energy is lost during engine braking. This is also known as a pumping loss. Diesels always intake the same amount of air, so they can compress it enough to autoignite the fuel. They vary the amount of fuel injected to the same volume of air. This means no throttle body or plate, so unless an extra exhaust restrictor has been added there is minimal engine braking on a diesel engine. [0] https://en.wikipedia.org/wiki/Compression_release_engine_brake https://en.wikipedia.org/wiki/Compression_release_engine_bra...
- ajross 1y agoTo some extent, but not really. Effectiveness of regenerative braking depends on having an extremely large battery that can sink enough current to stop the car. An EV can do that, hybrids at best help the brakes out some. You just can't charge the battery fast enough doing anything but a very slow rolling stop. My model Y can effect a very reasonable stop in traffic without touching the brake pedal except to hold the car at the end.
- jeffbee 1y agoIn normal driving hybrid regen is more than enough to do the job. Just look at the front wheels of any Prius. There are reasons all the Uber drivers choose the Prius.
- dyselon 1y agoWe finally gave up our Prius after 12 years, and we never changed the brakes once. The brakes were just peeking into the yellow on its last service upgrade. I was really impressed with how well the "normal" hybrid could take advantage of regenerative breaking, honestly.
- Helmut10001 1y agoI first changed the brakes on my Mitsubishi Space Star (combustion) after 13 years. It is a small car, less than 1000kg, so there is little for the brakes to do. If we produced more percentage of small cars, many environmental risks would be reduced. And btw.: The tires are now 19 years old and still good (less weight, less abrasion!).
- Tempest1981 1y agoRubber degrades with UV exposure, even if the tread depth is ok. Be careful, esp at higher speeds.
- deleted 1y ago[deleted]
- lazide 1y ago
- cperciva 1y agowhich is the whole point of hybrids Part of the point, not the whole point. Regenerative breaking is absolutely a win; but there can also be a significant benefit from allowing the ICE to remain in the RPM "sweet spot" rather than moving around a larger range.
- unglaublich 1y agoThis is how diesel-electric locomotives work too.
- ben-schaaf 1y agoThey also use the electric motor(s) for braking, but instead of going into a battery it goes into a bank of resistors.
- ddeck 1y agoI think you meant capacitors. Resistors would just dissipate the energy as heat. edit: Thanks for the correction. They do indeed use resistors and just dump the energy as heat. Unfortunate. Hopefully this will change as supercaps continue to improve. Maxwell tech's modules are already used in light rail, and looks like some work towards smaller locomotives in Switzerland here: https://www.osti.gov/etdeweb/servlets/purl/20823697 https://www.osti.gov/etdeweb/servlets/purl/20823697
- ahartmetz 1y agoCapacitors have pitiful energy storage capacity. Resistors is correct, unfortunately.
- trained6446 1y agoNope, resistors. The energy is dumped as heat. Dynamic brake
- ben_w 1y agoTo add to the other comments: https://en.wikipedia.org/wiki/Dynamic_braking https://en.wikipedia.org/wiki/Dynamic_braking
- fho 1y agoThe rear brake rotors on my Yaris hybrid are basically always rusty because they get used so little. After some time you just know when to start braking so you only use regen instead of the brakes.
- pkolaczk 1y agoI confirm and that’s an unpleasant surprise. Already had to replace the rear rotors and pads on my Highlander… because of rust. They should add some “brake cleaning” mode to temporarily disable regenerative braking.
- mschild 1y ago> They should add some “brake cleaning” mode Also known as breaking. You could just do that once in a while.
- whatevaa 1y agoSure, gonna slam on brakes while in front of you. It's 2025 and hybrids have enough software to automate some non-hybrid braking action.
- topsecret 1y agoYup, my Golf GTE is mostly used to fetch groceries, but every now and again I'll blast down a faster road and brake harder than just regen to keep the brakes themselves in good condition. It's almost second-nature at this point.
- dubbel 1y agoIf you don't break hard enough, it might still be the recuperation doing its work. Car producers can and do resolve this, e.g. iirc Audis don't use recuperation for the first breaking of the day. That way you don't have to remember to use the no-recuperation/break cleaning mode or break unnecessarily hard every now and then.
- 1y ago
- gambiting 1y agoIt does. My Volvo XC60 T8 PHEV is a 400bhp 2.2 tonne SUV and after over 5 years of ownership the pads are about 20% worn. And I don't drive like a granny either. The car just does most of its braking with the EV motor.
- joezydeco 1y agoSame here, XC40P8 and the pads are 10% used after 2.5 years. But I understand the factory tires are a bit stickier to create a quieter ride which may be throwing more rubber dust into the air. High torque launches don't help either. ;-)
- guidoiaquinti 1y agoI came across a really interesting video yesterday (https://www.youtube.com/watch?v=Aubi3cK8Ym0 https://www.youtube.com/watch?v=Aubi3cK8Ym0) that touches on brake-dust pollution. It also explains how regenerative (kinetic-energy) charging can cut down on heat pollution, something I hadn’t realized before. That’s actually a big deal for underground metro systems; for instance, the London Tube keeps getting hotter every year.
- spuz 1y agoYes indeed the London underground does use regenerative braking on many of their lines. The cool thing about a direct rail power system is that the voltage generated from trains that are braking can be fed back into the power rail to instantaneously power other trains on the same line that are accelerating. No need to carry the extra weight of a battery or flywheel. And like you say, it helps keep the tunnels cooler.
- KaiserPro 1y agoIt has to be the same segment, which is a bit of a pain to manage. The amount of power being fed in is getting close to megawatts.
- pjc50 1y agoUK stats are different: https://www.zap-map.com/ev-stats/ev-market https://www.zap-map.com/ev-stats/ev-market , possibly due to the shorter max travel distances. > As of the end of June 2025, there were 2,450,462 plug-in cars, with over 1,585,000 battery-electric cars and nearly 865,000 PHEVs, registered in the UK. > There are more fully electric cars than there are plug-in hybrids on UK roads and the gap has been widening. In 2021, fully electric cars accounted for 60% of all plug-in cars but with the increase in options, range and popularity of fully electric cars, and by May 2025 this has increased to 65%. (That stat does exclude non-pluggable-hybrids, but those are kind of pointless stalling of the transition off petrol)
- spuz 1y agoYour source doesn't consider non-plug-in hybrids also known as HEVs because zapmap are a company that sell charging services. The number of HEVs in the UK is about twice the the number of PHEVs so the total number of hybrids is still higher than the total number of BEVs. In 2024, 6% of vehicles on the road were hybrid compared with 3.7% fully electric. https://www.smmt.co.uk/more-than-a-million-evs-on-uk-roads-as-vehicle-ownership-reaches-new-high/ https://www.smmt.co.uk/more-than-a-million-evs-on-uk-roads-a...
- pjc50 1y agoI wonder which vehicles that is - is that predominantly the non-pluggable Prius?
- TreeInBuxton 1y agoThere is a wide variety, MHEV is quite popular here due to lack of home charging, as many people live in terraces, etc We have a selection of smaller popular hatchbacks with MHEV available (ie, the Hyundai i20) that I believe were not released in some markets The leasing culture for "luxury" cars is quite prevalent here too, and many new cars from popular brands such as Land Rover are at minimum MHEV from new nowadays, in order to get fleet emissions down
- seb1204 1y agoMany hybrids are not driven to max regenerative breaking. You need to drive and look ahead to make good use of the regeneration. Short distance breaking is still fast and using the discs.
- londons_explore 1y agoHard braking is an insane power. Eg. A typical 4,400 lb car emergency stopping from 80 mph has a braking power of 940 horsepower. Hybrid cars have smaller motors, inverters, and battery packs - and none of those components can absorb 940 horsepower! A 2nd gen prius battery for example has a max in/out of 30 horsepower.
- potato3732842 1y agoAlways sketches me out using regen for a serious grade decent while laden or towing. I have a sneaking suspicion that one day it's gonna error out and disable itself because too much power and I'll be down to just normal brakes.
- londons_explore 1y agoIt will disable itself if your battery is already full... Some cars it's quite an abrupt change from the regen braking to the hydraulic brakes.
- chakintosh 1y agoOn both my Volvo PHEVs I often look at the brake discs and find them rusty from the amount of regen braking. it almost completely eliminates conventional braking unless it's for collision avoidance.
- dboreham 1y agoMy EV turns regenerative braking off for the first use of brakes after beginning a journey, to avoid the rusting disc syndrome.
- masklinn 1y agoWhat car brand is it? I've read that Audi and Porsche do that. Also is it only pedal braking? Or does it "fake" things out if you use one-pedal driving?
- tkj922 1y agoSo your primary and emergency brake system elements are rusty and that is now somehow a good thing?
- michaelcampbell 1y agoBrake rotors will noticeably rust overnight if left in wet conditions.
- ZeroGravitas 1y agoYes, but only to some degree. Quote from the actual report: > As the level of electrification of a vehicle rises, the dependence on regenerative braking also increases, thus lowering PM emissions from brake wear. Based on recent evidence [30], regenerative braking can reduce, in the worst- case scenario (i.e. highest usage of mechanical brakes or equivalently lowest usage of regenerative braking), brake wear emissions by 10-48% for hybrid electric vehicles (HEVs), 66% for plug-in hybrid electric vehicles (PHEVs), and 83% for battery electric vehicles (BEVs
- deleted 1y ago[deleted]
- m463 1y agoThis makes sense since vehicles with bigger batteries can absorb more energy with regenerative braking. I remember decades ago where they figured out the horsepower of a high-end porsche to go 0-100-0, and if the acceleration horsepower expended was 500hp, the deceleration horsepower absorbed by the brakes was probably 1000 hp. I wouldn't be surprised if hybrids could only absorb 10 hp, while bigger cars could absorb 50. One thought - if any of these manufacturers provided "braking resistors" like diesel-hybrid locomotives use, regenerative energy could be electrically turned into heat, instead of mechanically by wearing the brakes. using resistors would be "green".
- infecto 1y agoI have not seen many if any Hybrids that use regen to the same degree as an EV.