• littleomid@feddit.org
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    6 days ago

    From experience, having started half hour later and having arrived about an hour earlier over 500ish km going the same exact roads at the same time, that doesn’t sound right. Is car dependent.

    Going as fast as possible with a family car will consume as much petrol as a sports car of similar engine size going max speed, however the sports car is going to be about 50% faster.

    If you drive a Prius at a speed which is “just cruising” for a sports car, it will use more fuel.

    • HansGruber@sh.itjust.works
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      6 days ago

      So… You are saying that a family station wagon going 200kmph consumes as much as a sports car going 300kmph with the same engine size?

      Sir I call your statement utter bullshit and here’s why:

      Let’s take the Mercedes AMG A 45s 4Matic+ with 1991cm3 and 421hp. Not really a sports car but who the heck produces sports cars with the same engine size like normal station wagons? And the VW Passat Variant with the 2.0 TSI engine and 190hp. The VW consumes up to 20L/100km at 200kmph and the Mercedes going 270kmph (I know not even 50% faster) consumes 50l/100km going full throttle.

      Give me any other modern good quality cars that prove me wrong and I’ll apologise but till then that’s not even close to make sense. Heck the sport’s car’s have to cool the engine with fuel to not overheating, how on earth will your claim ever work?

      Are you even allowed to drive a car yet?

      • littleomid@feddit.org
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        5 days ago

        You have a vastly different opinion of family car and sports car than I do. Take a “normal” and affordable family car with a 2l with around 130hp and compare it with a “normal” affordable sports car, with a 2l producing 200hp. The sports car will go faster for the same amount of fuel consumed, even if you ignore all the other things and just focus on the aerodynamics.

        You can compare something like a TT8j and a Golf maybe. That’s the same engine, tuned differently, in a different body. If you are going to be disrespectful, just refrain from replying.

        • HansGruber@sh.itjust.works
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          5 days ago

          Well sorry how I phrased that. But explain to me how that works.

          I already did some math. Ok the golf is going what? 130? Then the TT goes 195kmph.

          The VW EA888 is not available as 130hp edition, especially not in a Golf, there it’s used in the R Models or as 190hp edition. The smallest equivalent engine I could find was the Golf VI 1.8T with 160hp. The CDAA engine.

          But ok, let’s just ignore the engines for now, focus on resistance.

          In this calculation I use a density of 1.29kg/m³.

          Audi TT8J with the spoiler retracted has a drag coefficient of 0.31 and that’s really impressive. We have a surface area of 2.09m² and a speed of 195kmph.

          That results in 1226.12N drag force applied to the Audi TT

          The Golf has CW values ranging from Golf 1 with 0.42 to 0.27 Golf 7 Blue motion.

          But let’s assume we have a Golf 6 from 2010 with 0.31 CW (sounds familiar) a surface area of 2.23m² and the speed of 130kmph. That results in 581.44N drag force.

          Explain to me like, how will the Audi manage to go that fast, with that drag force applied and consume the same amount of fuel like the Golf? I mean even the engine should be the same size. So either the Audi TT has a magical rolling resistance that he can compete with the golf fuel consumption. Don’t know how the math here work’s, especially in regard that the golf is 100kg lighter.

          Are there much more efficient air conditioning systems/assistant systems in the sports car that reduce the fuel consumption?

          I don’t know… The Audi you mentioned consumes 7,7L/100km. Let’s take the worst engine the Golf 6 has, that has less horsepower that the Audi: the VW EA 113 1.6L with 102 hp. Btw the same engine plattform like the Audi’s engine. That consumes 7.1L/100km.

          So please, enlighten me. How can the “sports car” go 50% faster and consume the same amount of fuel? The drag force is more than doubled. The engine consumes by default more. How?

    • kossa@feddit.org
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      6 days ago

      As I wrote: on long distances it can make a difference. But blasting for 3,5 hours 200 is not safe, so if people do that, they’re endangering themselves and others.

      And obviously different cars use different amounts of fuel to achieve the same feat. But if you took the sports car at 100 only it saves a lot. Power (phys.) is dependent to the third power of 3 of the velocity. It’s just physics. When you double the velocity it’s thus way, way, WAY more fuel than just double the fuel.

      • littleomid@feddit.org
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        5 days ago

        A sports car doesn’t have the same aerodynamics as a family hatchback though. You can’t compare them like this directly.

        • kossa@feddit.org
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          5 days ago

          No, that’s why I didn’t.

          General physics apply to the sports car as well, though. The sports car still uses way, way, way more gas for a higher velocity.

          My point is: gas usage is not proportional with speed. It is factor ^3. People underestimate that.

          So when I cruise on a flat surface at 100kph, I use some 4.7 litres with my car. If I go 120kph, a lot of people would expect an increase of 20%, at max, so roughly 5.6 litres. But it gets to some 6.5 litres, an increase of almost 40%. And if I went 150 or above that shit gets crazy.

          The same applies to the sports car. If people calculate “I drive twice as fast, it’ll cost me twice as much”, that’s a crazy miscalculation.

          • littleomid@feddit.org
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            5 days ago

            Nobody said that though. It’s just not always to the power of three. It can’t be, if you consider aerodynamics and the shape of the car. A pointy rocket doesn’t use the same amount of fuel to go at a certain speed as a G wagon, all other things remaining equal.

            • kossa@feddit.org
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              5 days ago

              It is, see e.g. here

              The sports car has a better drag coefficient and less surface area, that is why at the same speed it needs less power. The “aerodynamics” are factored in only in those coefficients. But the velocity is the dominating part, as it is cubed in that equation.

              But still, I am not comparing a sports car to a station wagon. I compare a sports car to itself at higher velocities. And contrary to popular belief, higher speeds result in an unproportional excess in fuel consumption.