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I'm really surprised the Europe big car manufacturers spent so much effort on small Diesel engines instead of Turbo gasoline engines. My theory is the fact tha

by izend 8y ago

I'm really surprised the Europe big car manufacturers spent so much effort on small Diesel engines instead of Turbo gasoline engines. My theory is the fact that having a majority of Diesel vehicles in Europe lowers their oil consumption vs Gasoline engines, hence, lowers their CO2 production but with the extremely negative fact of increased local smog.

zwieback 8y ago
Diesel was always popular due to high fuel efficiency. Since diesel also has lower CO2 emissions they really took of in the 90s. However, gas engines are catching up in both areas.
trhway 8y ago
Modern small diesels are also turbo, they just more efficient than the gas ones.
beberlei 8y ago
Diesel has a much lower tax than gasoline per liter. The car manufacturers just serve the higher demand for diesel cars, because it is cheaper to operate monthly.
- gambiting 8y ago
  There's at least few EU countries where Diesel is much more expensive than petrol at the moment. People like diesels because it's actually hard to get huge fuel consumption with those, while if you're not particularly careful any turbo petrol will drink fuel quickly. I had a 1.6dCi Qashqai and that car would not burn more than 10L/100km, no matter what I did or how aggressively I drove. Zero chance. I also have a 1.2TSI petrol Polo, and you can easily make it use 20L/100km if you drive it like a maniac - you have to be actively careful to keep it in the 6-7L/100km range, while the 1.6dCi would easily do 5L/100km without really thinking about it.
  - danieldisu 8y ago
    Wow, I have a Seat with the same 1.2 engine and is really really hard for me to surpass the 8L/100. Maybe driving very fast can get you over these numbers but driving in the legal limit of most countries won't make you burn that much fuel!
    - gambiting 8y ago
      It has absolutely nothing to do with driving above the speed limit -as a matter of fact driving at a completely legal 120km/h won't use anywhere near as much fuel because you are travelling pretty fast and not accelerating anymore, so the consumption will be decent. But try accelerating from every stop in the city all the way to the redline, pedal to the floor, but never going above 50km/h - you would never go above the speed limit, but the tank would disappear in no time at all. I'm certain that if I tried I could burn the entire 50L tank of the Polo in ~250km, by just keeping it in high revs and accelerating hard(as hard as you can in a 90bhp Polo anyway) and frequently. The injectors will happily keep feeding the engine more and more fuel as you do this, while diesel common rail systems have almost a hard limit of how much fuel they can inject - no matter what you do you won't go above certain values.
      - Y_Y 8y ago
        > not accelerating anymore maybe in a frictionless vacuum! At high speeds the force you have to exert to counter wind resistance is less than what you need to gently accelerate when going slowly.
    - growlist 8y ago
      Agree with you on this. I had a Golf 1.4 TSI which I drove quickly and it was amazingly frugal.
rb808 8y ago
Exactly, global warming is the main environmental target in the news and laws. NOx is secondary.
Pulcinella 8y ago
Diesel emissions standards are lower in Europe than in US. So that makes diesels easier to produce and sell in Europe. I believe, as you said, diesels also have lower CO2 emissions per mile than gasoline engines. The problem is the increased SOx and NOx emissions as well as soot emissions that contribute to smog. In theory, Diesel engines should have much lower smog than gas engines because Diesel engines require excess oxygen rather than stoichiometric ammounts like in gas engines. The problem is that diesel fuel doesn’t vaporize nearly as well as gasoline, so you end of with tiny droplets of diesel in the engine rather than pure vapor. So even though there is excess oxygen, the O2 can’t get to the inside of the droplets and the engine heat basically cooks them into soot.
- seanalltogether 8y ago
  Is this simply because diesel is less refined, so it has less overall hydrocarbons then gasoline and higher amounts of other junk molecules?
  - ihsw2 8y ago
    Perhaps but car manufacturers will point fingers at higher sulfur content in lower-graded diesel. Other issues like fuel filters and water traps performing sub-optimally (due to age or lack of replacement/maintenance) can introduce contaminants that further exacerbate the situation, surely there are sensors for this.
    - growlist 8y ago
      People also deliberately disable the DPF between annual checks here in the UK. The DPF equals lower emissions but also worse mpg.
  - abakker 8y ago
    Diesel is not really "less refined" it is a different distillate of crude oil, and contains heavier molecules. I think major contributor to its worse atomization is it's higher viscosity and lower vapor pressure at room temperature. It just evaporates a lot less readily. If you've never handled gas and diesel, diesel feels a lot oilier and if you soak a rag with diesel vs gas, the gas will evaporate a lot sooner.
gascan 8y ago
Small turbodiesels were way ahead of small gasoline engines for decades in fuel economy, power, and so forth. Diesel, which uses direct injection and compression ignition, has always been a natural fit with turbocharging, which makes them intrinsically suited to the paradigm of a small engine for efficiency with a turbo for power. They also intrinsically have great low-end torque, which complements the top-end power of turbos. Turbo gasoline engines were hard to make well, I gather mostly due to predetonation. Gasoline engines historically use manifold injection and spark ignition, which limits compression ratios. However, with advances in technology, particularly in engine computers & sensors, small turbo gas engines have recently become far more competitive. So, basically, from the vantage point of 2018 turbodiesels might seem like a questionable choice- but ten or twenty years ago, good small turbocharged gasoline engines mostly didn't exist.
- rconti 8y ago
  This is my understanding as well. Highly advanced knock and temperature sensors, high pressure gasoline direct injection, turbochargers, and high compression ratios in gasoline engines are a relatively new combination. Gasoline engines have seen huge leaps in efficiency in the past decade.
- blattimwind 8y ago
  Personally I find it much easier to drive Diesels in a fuel-economic fashion. With gasoline cars you really have to watch it.
InternetOfStuff 8y ago
Because of their process, diesels are also more efficient at partial loads (e.g. city driving) than petrol engines. This gives you an efficiency advantage right off the bat.

by izend 8y ago

zwieback 8y ago

Diesel was always popular due to high fuel efficiency. Since diesel also has lower CO2 emissions they really took of in the 90s. However, gas engines are catching up in both areas.

trhway 8y ago

Modern small diesels are also turbo, they just more efficient than the gas ones.

beberlei 8y ago

Diesel has a much lower tax than gasoline per liter. The car manufacturers just serve the higher demand for diesel cars, because it is cheaper to operate monthly.

gambiting 8y ago
There's at least few EU countries where Diesel is much more expensive than petrol at the moment. People like diesels because it's actually hard to get huge fuel consumption with those, while if you're not particularly careful any turbo petrol will drink fuel quickly. I had a 1.6dCi Qashqai and that car would not burn more than 10L/100km, no matter what I did or how aggressively I drove. Zero chance. I also have a 1.2TSI petrol Polo, and you can easily make it use 20L/100km if you drive it like a maniac - you have to be actively careful to keep it in the 6-7L/100km range, while the 1.6dCi would easily do 5L/100km without really thinking about it.
- danieldisu 8y ago
  Wow, I have a Seat with the same 1.2 engine and is really really hard for me to surpass the 8L/100. Maybe driving very fast can get you over these numbers but driving in the legal limit of most countries won't make you burn that much fuel!
  - gambiting 8y ago
    It has absolutely nothing to do with driving above the speed limit -as a matter of fact driving at a completely legal 120km/h won't use anywhere near as much fuel because you are travelling pretty fast and not accelerating anymore, so the consumption will be decent. But try accelerating from every stop in the city all the way to the redline, pedal to the floor, but never going above 50km/h - you would never go above the speed limit, but the tank would disappear in no time at all. I'm certain that if I tried I could burn the entire 50L tank of the Polo in ~250km, by just keeping it in high revs and accelerating hard(as hard as you can in a 90bhp Polo anyway) and frequently. The injectors will happily keep feeding the engine more and more fuel as you do this, while diesel common rail systems have almost a hard limit of how much fuel they can inject - no matter what you do you won't go above certain values.
    - Y_Y 8y ago
      > not accelerating anymore maybe in a frictionless vacuum! At high speeds the force you have to exert to counter wind resistance is less than what you need to gently accelerate when going slowly.
  - growlist 8y ago
    Agree with you on this. I had a Golf 1.4 TSI which I drove quickly and it was amazingly frugal.

rb808 8y ago

Exactly, global warming is the main environmental target in the news and laws. NOx is secondary.

Pulcinella 8y ago

Diesel emissions standards are lower in Europe than in US. So that makes diesels easier to produce and sell in Europe. I believe, as you said, diesels also have lower CO2 emissions per mile than gasoline engines. The problem is the increased SOx and NOx emissions as well as soot emissions that contribute to smog. In theory, Diesel engines should have much lower smog than gas engines because Diesel engines require excess oxygen rather than stoichiometric ammounts like in gas engines. The problem is that diesel fuel doesn’t vaporize nearly as well as gasoline, so you end of with tiny droplets of diesel in the engine rather than pure vapor. So even though there is excess oxygen, the O2 can’t get to the inside of the droplets and the engine heat basically cooks them into soot.

seanalltogether 8y ago
Is this simply because diesel is less refined, so it has less overall hydrocarbons then gasoline and higher amounts of other junk molecules?
- ihsw2 8y ago
  Perhaps but car manufacturers will point fingers at higher sulfur content in lower-graded diesel. Other issues like fuel filters and water traps performing sub-optimally (due to age or lack of replacement/maintenance) can introduce contaminants that further exacerbate the situation, surely there are sensors for this.
  - growlist 8y ago
    People also deliberately disable the DPF between annual checks here in the UK. The DPF equals lower emissions but also worse mpg.
- abakker 8y ago
  Diesel is not really "less refined" it is a different distillate of crude oil, and contains heavier molecules. I think major contributor to its worse atomization is it's higher viscosity and lower vapor pressure at room temperature. It just evaporates a lot less readily. If you've never handled gas and diesel, diesel feels a lot oilier and if you soak a rag with diesel vs gas, the gas will evaporate a lot sooner.

gascan 8y ago

Small turbodiesels were way ahead of small gasoline engines for decades in fuel economy, power, and so forth. Diesel, which uses direct injection and compression ignition, has always been a natural fit with turbocharging, which makes them intrinsically suited to the paradigm of a small engine for efficiency with a turbo for power. They also intrinsically have great low-end torque, which complements the top-end power of turbos. Turbo gasoline engines were hard to make well, I gather mostly due to predetonation. Gasoline engines historically use manifold injection and spark ignition, which limits compression ratios. However, with advances in technology, particularly in engine computers & sensors, small turbo gas engines have recently become far more competitive. So, basically, from the vantage point of 2018 turbodiesels might seem like a questionable choice- but ten or twenty years ago, good small turbocharged gasoline engines mostly didn't exist.

rconti 8y ago
This is my understanding as well. Highly advanced knock and temperature sensors, high pressure gasoline direct injection, turbochargers, and high compression ratios in gasoline engines are a relatively new combination. Gasoline engines have seen huge leaps in efficiency in the past decade.
blattimwind 8y ago
Personally I find it much easier to drive Diesels in a fuel-economic fashion. With gasoline cars you really have to watch it.

InternetOfStuff 8y ago

Because of their process, diesels are also more efficient at partial loads (e.g. city driving) than petrol engines. This gives you an efficiency advantage right off the bat.