Comment on Hehe

• boonhet@lemm.ee ⁨1⁩ ⁨week⁩ ago

  I’ve never owned a car that small and I’ll preface this with saying that of course the tiny car wins the fuel economy competition. My friend also has a tiny car with a 1.2 liter engine that absolutely beats anything I’ve ever owned in terms of fuel economy in the city. However, sustained highway mpg of 40 (just under 6l/100km) for a large luxury sedan with an ancient 4 speed auto box is pretty impressive if you consider that at the time, my other friend’s newer, significantly smaller, lighter and manual transmission equipped 1.6 liter Mazda 3 averaged 36 mpg or 6.5l/100km on the highway.

  Of course the giant (by European standards) beast’s fuel economy dropped off if I gunned it from a red light in the city. Starting and driving in the city in -30C was also absolutely brutal for the fuel economy. But the fact that at least on the highway, for which it was truly made, it beat a smaller, lighter car with a smaller engine says a lot IMO. The beast ran around 1500-1600 rpm at 90 km/h, whereas the Mazda was more like 2000-2500 IIRC, in 5th/top gear. If you wanted to overtake anyone in the Mazda, you generally had to drop from 5th into 3rd gear as well, whereas my Chrysler didn’t really NEED to downshift from 4th to 3rd, but it certainly made the whole ordeal take a lot less time. Probably if the Mazda had had a slow revving 2 liter engine with decent low-end torque, it could’ve been geared entirely differently and would’ve used significantly less fuel. Underpowered engines don’t get the best fuel economy - appropriately sized engines for a car do. Keep in mind that my Chrysler was from 1999. It had a 4 speed transmission. My friend’s Mazda was a 2005 model. Modern cars tend to have turbos and 7-10 speed transmissions to help keep them in efficient RPM ranges for good torque-specific fuel consumption too.

  Long term average for the Chrysler (300M) with a bunch of city driving included was 10 l/100km, or 23 mpg. Obviously no match for your ecobox, but still better than my current 2.5 liter Subaru Outback, which is 14 years newer, 21 CM shorter and 14 CM narrower than the 300M, and has similar gearing (it’s a CVT, but I get similar RPM ranges at similar speeds generally). The Outback of course does have the disadvantage of extra height in this case though.

  So no, I never wanted to say that a bigger engine is always more economical. There are clear cases where there is no need for a big engine. Modern technology has also helped small engines deliver power in a much better fashion. The 3 cylinder 1.0 engine they put in some Škodas nowadays has about the same max power rating as my friend’s 1.6 liter Mazda did, but it has more torque AND at lower RPMs. The VAG 1.4 or 1.5 or whatever TSI with 110kW? It gets WAY more torque at MUCH lower RPMs compared to the 1.6. Hell, the 2.0 variants they put in the new Golf GTI, R, etc, are torque monsters that also blow my 300M’s N/A 3.5 liter out of the water. These engines can drive bigger cars without any issues. Of course this all comes with the cost of added complexity. Turbo, direct injection, etc.

  So TL;DR: My claim that small engines are less economical pertains to underpowered naturally aspirated engines that lack the torque for the car they’re trying to move, versus adequately sized engines with adequate torque. Small car with small engine is of course still going to be more economical. Medium sized and big cars with gutless engines are where my point applies. Modern tech expands the torque range of small engines so you can’t compare it anymore anyway, you can now put smaller engines in cars without losing driveability and fuel economy.

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