in 1997 Toyota introduced the first commercially successful hybrid, the Prius.
pictured: the original Prius:
the basic motivation of the tech is that Combustion Engine Efficiency is lowest at low loads, and overall efficiency can be improved by turning the engine off at those low loads and driving in electric mode under low speed coasting conditions.
let’s look at BSFC or Brake Specific Fuel Consumption map for a typical good car engine below:
it can take a while to understand the graph but once you do it’s very clear. ( ask me if you don’t understand what the graph shows - and don’t worry about anything below horizontal axis / negative power / engine braking ).
also something crazy to me is that efficiency versus power for combustion engine has overall the same curve as efficiency versus power for a computer power supply … that is it zero at zero load, then peaks at about 1/3 load and gradually declines slightly towards 100% load … better not to think about it or the simulation might crash !
anyway, the smallest ( 230 ) contour represents maximum efficiency ( lowest fuel consumption per unit of power produced ), but 250 is still very close to 230 so let’s say that if we stay within 250 contour we are still operating optimally.
this means we should never run the engine below 1,000 rpm or at torque below about 40% of max torque for any given RPM or we will be wasting fuel for not much energy output. another way to put it is we should never run the engine below 10% of max power if we want optimum fuel economy. so for a 200 hp engine we would want to switch over to electric at around 20 hp mark. to have a smooth transition we would want some reserve, so let’s say 40 hp electric motor. congratulations - you have built a Toyota Camry Hybrid - the number one car used by NYC Uber Drivers for its fuel economy.
pictured: Toyota Camry Hybrid NYC Taxi Cab:
i had this same model Camry Hybrid myself, except mine was fully loaded with every option like Genuine Leather, JBL Audio, 360 camera etc. i got mine within weeks of it first becoming available. this was more than 6 years ago.
by the way hybridization is only one solution tried to improve efficiency at low engine loads. the cause of low efficiency at low loads in a combustion engine is mainly PUMPING LOSSES caused by the throttle. this is because for catalytic converters to work properly combustion has to occur in a somewhat narrow range of fuel to air mixture ratios, so when you reduce power by reducing fuel you must also reduce air ( create partial vacuum ) which is accomplished by partially closing the throttle which then begins to act as an engine air brake, hence pumping losses.
the most obvious “solution” to this problem was Diesel engines, which simply do not have a throttle to begin with, which is why they are so efficient. of course that is also why they are so polluting as well, and why ultimately they had to be given up on. i put “solution” in quotes because it literally solves nothing - it simply ignores pollution. All modern engines use Direct Injection anyway, which was the innovation behind Diesel cycle in 1893 or over 130 years ago !
i was actually telling everybody Diesel was shit for years before Dieselgate but Low IQ is Low IQ. the same animals that used to bleat Diesel Diesel Diesel - now bleat Electric Electric Electric - because sheep must bleat - there is nothing else for them to do - it’s what they are. did you really think they can objectively analyze technology ? they just sniff around ( as dogs would sniff each other’s butts ) to see what is “cool” these days then proceed to bleat about “amazing technology” …
pictured: Diesel Exhaust from School Bus
actually there was a solution to diesel pollution which involved a tank of special liquid ( called DEF for Diesel Exhaust Fluid ) that was injected into exhaust to clean it … ultimately it was simply not an acceptable solution for passenger vehicles due to laziness and stupidity of users and their irrational desire to have something for nothing. i did drive a Bluetec Mercedes Van ( that uses this tech ) while moving from NYC to NJ so this system is viable in commercial applications but consumers don’t want to deal with having to fill up DEF, which also happens to smell.
pictured: DEF tank and pump:
consumers in Europe ( where gas is very expensive ) demanded diesels but didn’t want to use DEF so VolksWagen cheated, got caught and brought down Diesel with it. and thank G-d for that. Diesel was trash and needed to die. Unfortunately now we have EVs which are even worse.
pictured: child slaves mining chemicals for EV batteries:
yet another solution to pumping losses problem tried by BMW was valvetronic, which created the vacuum using valve timing instead of throttle … i actually had valvetronic on my 2008 BMW … unfortunately the system proved to be a nightmare with BMW mechanics refusing to buy any cars that have valvetronic in them, so many new BMWs do not use the system anymore …
yet another solution tried was cylinder deactivation, which was fairly common in V8 engines … which is when under low loads the enigine turns off some of the cylinders … the obvious downside to that is the engine becomes rougher and sometimes also creates an odd drone noise because the exhaust is designed for a different number of cylinders … nobody ever thought this was a good solution but it was a relatively cheap and simple way to save gas in V8 engines … many people ended up buying aftermarket chips to disable cylinder deactivation in their cars because of how annoying it was …
finally TURBOCHARGING was yet another workaround, which didn’t reduce air pressure at low loads … but rather increase it at high loads … which combined with a smaller engine size effectively accomplished the same thing … with the price being turbo lag …
pictured: cutaway view of a Turbocharger:
there may of course be other solutions i don’t know about for example i literally just now read about how Mazda uses increased exhaust gas recirculation so i guess instead of vacuum they just replace air with exhaust to effectively bring fuel to oxygen ratio closer to target … but regardless the issue remains the same … at partial loads efficiency of combustion engines goes down …
bottom line - the industry has struggled with this same fundamental issue of pumping losses and low partial load efficiency for a LONG TIME and has made MANY ATTEMPTS to try to deal with it.
the Hybrid Tech is simply the most advanced and most effective solution to the same problem that Diesel, Valvetronic, Cylinder Deactivation and Turbocharging all tried to solve.
although hybrid tech can be used in combination with any of these other technologies there is relatively less of a benefit to any of these technologies when combined with hybridization as opposed to when using them on their own. this is for example why Diesel Hybrids never became a thing even though many hypermilers were clamoring for them - but they simply didn’t understand that it makes no sense to use two redundant systems to accomplish the same thing.
the modern approach is to combine hybridization with turbocharging while abandoning both diesel and cylinder deactivation. this is because unlike cylinder deactivation and diesel tech, turbocharging actually increases performance so it is worth it even if on a hybrid system there will only be a small improvement in efficiency since pumping losses are already minimized by engine shutting off.
at one point Ferrari said that all their future cars will be EITHER Hybrid OR Turbo. so to some extent hybrid and turbo technologies do compete against each other … and yet ultimately the industry has started to move towards using BOTH hybrid AND turbo IN THE SAME ENGINE.
i have no issue with that. my car is both hybrid and turbo. the car i want is also both hybrid and turbo. i can only guess that having that flexibility / overlap allows for a smoother transition between gas and electric power.
although toyota’s naturally aspirated hybrid system had very smooth transitions it relied on a rather expensive and slow planetary system to achieve this smootheness. even toyota has now moved on to a more conventional approach that uses an automatic transmission with gears and an engine with turbocharger in their “performance” hybrids.
so while prius and camry hybrid retain the original toyota hybrid system many of the lexus hybrids now use the same system as used for example by BMW hybrids. namely a regular turbo automatic setup but with torque converter replaced by electric pancake motor and clutch setup.
pictured: 2024 Porsche Panamera’s 8 speed double clutch transmission with integrated Electric Motor for the E-Hybrid system:
the original toyota system of course had no gears, no turbo and employed a DUAL MOTOR planetary setup. it is still a good system for cars like Prius and Camry that are focused on efficiency and smoothness but no performance vehicles have ever used this system.
pictured: Toyota Hybrid Synergy Drive Dual Motor Planetary e-CVT:
