Please register to participate in our discussions with 2 million other members - it's free and quick! Some forums can only be seen by registered members. After you create your account, you'll be able to customize options and access all our 15,000 new posts/day with fewer ads.
This thread for technologies that improve fuel economy that have a dubious effect on personal enjoyment of driving, maintenance costs or safety. The worst average fuel economy for new US automobiles occurred in 2004.
I'll start off with a dozen fuel saving engineering decisions
Plug in hybrids and electric vehicle are obvious
Hybrid vehicles that use an auxiliary motor to propel the car
Reduction of displacement - the most obvious fuel saving engineering decision
Reduction of vehicle weight - another obvious fuel saving engineering decision
Front Wheel Drive - Also decreases the complication and the price of the vehicle. But it greatly improves fuel economy over rear wheel or all wheel drive.
Reducing the number of cylinders. Most commonly from 8 or 6 to 4, but now 3 cylinder vehicles are coming back into vogue.
Turbo- downsizing or the use of Turbocharged engines to reduce the displacement or the number of cylinders. Nearly every automaker has done it. For example Subaru introduced its first turbocharged engine in 1983 for the GL Turbo Wagon, and its first 6 cylinder in 1988, but they stopped selling 6 cylinder in 2019 to exclusively use smaller displacement turbocharged engines for power. Most of their competitors still use 6 cylinders for their three row SUVs, but Subaru sells the Ascent with 4 cylinders and CVT.
Non hybrid start - stop: to reduce time spent idling
Gasoline direct injection (GDI) is a fuel delivery system in gasoline internal combustion engines. It utilises a high-pressure common rail accumulator assembly which injects the fuel mixture directly into the engine's combustion chambers.
Eliminating Manual Transmission - also makes it easier to sell cars to a wider range of people. Up until around 2010 MT had better mileage than AT, but no longer!
Automatic Transmissions with multiple gears - although Toyota was still selling a 3 speed AT vehicle as late as 2002 (a Corolla), usually by multiple we mean more than six since no traditional transmission had 7 or more gears.
Continuous Varable Transmission (CVT) - makes huge improvements in fuel efficiency. but many people feel at the expense of vehicle lifespan.
President Trump in 2018 in the EPA statement blamed President Obama's more stringent Corporate Average Fuel Economy (CAFE) requirements passed in 2011 for SOME of the marked increase in motor vehicle fatalities. His proposal was to freeze the CAFE requirement at their 2020 level for at least 5 years.
1972: 54,589 peak motor vehicle fatalities in the United States
2011: 32,479 lowest motor vehicle fatalities in the United States since the 1940s (1.10 fatality per 100 million vehicle miles travelled)
2021: 42,915 latest motor vehicle fatalities in the United States (1.33 fatality per 100 million vehicle miles travelled)
Even accounting for vehicle miles travelled the death rate is still going up.
Often cited is the act of "picking the low-hanging fruit" or the "law of diminishing returns". Automakers have exploited most of the simplest fuel saving techniques and are moving on to ever more complex designs which increase overall acquisition cost and maintenance cost.
Of course, the simplest solution would be to return to vehicles with engines that produce substantially below 100 hp, but most automakers consider that to be economic suicide. Outside of the 78 hp Mitsubushi Mirage there are several models with around 120 hp, and they all sell very poorly. Examples are the 2022 Nissan Versa with 122 hp; the 2022 Hyundai Accent & the Kia Rio with 120 hp; and the Toyota Prius with 121 hp. The Chevy Spark is definately terminated, and most people believe the Ford Fiesta will not return.
The Nissan Sentra (140 hp) and the Honda Civic (158 hp) are probably the best selling cars with low horsepower. Even the Toyota has increased their standard engine in the Corolla from 139 hp to 169 hp.
The Mazda 3 sedan produces 155 hp and the Subaru Impreza produces 152 hp.
Last edited by PacoMartin; 07-29-2022 at 08:15 PM..
Fuel saving tires. Some save more fuel than others but the trade off is reduced traction, longer stopping distance, and a worse ride. Some models sacrifice some fuel saving to improve on the negatives while others maximize fuel savings at the expense of safety.
A car with a stiffer suspension has faster weight transfer and then runs tighter lines. The tighter line uses less fuel but is in contrast to the viewpoint of cars just driving straight down the road. However, the faster weight transfer works the tires harder and therefor sufficient tire width is needed. Then if wider tires are needed they would likely have shorter sidewalls for matching the response of the suspension. However, wider tires do have increased tire drag just when driving straight down the road.
But consider how fast a responding car that the driver can handle.
For cars without smooth undersides, a front air-dam reduces aerodynamic drag. Also, front-end aerodynamic lift is reduced but without reducing rear-end lift. And so an aerodynamic imbalance is possible. However, a fastback vehicle shape already has minimum rear-end aerodynamic lift. Or a rear lip spoiler reduces drag and rear lift by a small amount. An upside-down aircraft-wing on the rear increases drag but of course reduces lift.
For cars with smooth undersides, then front splitters are used to reduce aerodynamic drag.
A car with a stiffer suspension has faster weight transfer and then runs tighter lines. The tighter line uses less fuel but is in contrast to the viewpoint of cars just driving straight down the road. However, the faster weight transfer works the tires harder and therefor sufficient tire width is needed. Then if wider tires are needed they would likely have shorter sidewalls for matching the response of the suspension. However, wider tires do have increased tire drag just when driving straight down the road.
But consider how fast a responding car that the driver can handle.
For cars without smooth undersides, a front air-dam reduces aerodynamic drag. Also, front-end aerodynamic lift is reduced but without reducing rear-end lift. And so an aerodynamic imbalance is possible. However, a fastback vehicle shape already has minimum rear-end aerodynamic lift. Or a rear lip spoiler reduces drag and rear lift by a small amount. An upside-down aircraft-wing on the rear increases drag but of course reduces lift.
For cars with smooth undersides, then front splitters are used to reduce aerodynamic drag.
Now consider the aerodynamics of a lowered car
.
You are correct regarding the underside of a vehicle being critical to efficiency. This, and the wells for the tires, make up a HUGE factor in efficiency.
I am not an engineer but a fan of F1 racing. What the F1 race car engineers have done in recent years is to produce smaller and more efficient engines that are as powerful as the former F1 8-cylinder engines. The present F1 race cars are super aerodynamic, lightweight, and have motors that produce in excess of 1,000 HP. Not only that, they also incorporate regenerative braking and electric motors that are used to boost total HP. This boost is from 80 HP-a little over 100 the driver can use for a few seconds x each lap. The electric motors do produce in excess of 300 HP, but F1 restricts the amount of HP that can be used. So, in excess of 1,000 HP, a F1 car uses somewhere near 6 MPG of fuel at engine continuously near maximum RPM.
The remaining 300-or-so bhp is produced by two electric motors attached to the ICE and working in harmony with it.
The first of these is the so-called MGU-K – the kinetic energy recovery unit. In simplistic terms, this ‘harvests’ energy produced under braking that would otherwise be lost. Under braking, the motor-generator acts via a flywheel to generate electricity, which is then stored in a 20kg lithium-ion battery housed within the PU. When the MGU-K is used ‘in reverse’ – as a motor – it can contribute up to a regulated maximum of 120kW of power – equivalent to 160bhp.
The second motor-generator unit – the MGU-H – converts heat energy into electricity, to be deployed in a similar way – at the driver’s command via his right foot and throttle.
The MGU-H is located between the turbine and compressor of the turbocharger, on top of the V6 engine. When exhaust gases spin the turbine, they also ‘spin up’ the MGU-H, via a shaft that connects the turbine and compressor. This produces electricity, also stored in the battery. Under acceleration, the electricity is used in part to help eliminate turbo lag, by spinning the compressor in addition to the flow of exhaust gases over its blades. The energy that can be harnessed by the MGU-H is not restricted, as it is for the MGU-K.
Working in unison these three motors and an energy store (battery) represent by far the most complex – and expensive – ‘engines’ ever used in Formula 1. They’re also, however, dramatically more efficient than any ever used in the sport. Comparably powerful 3.0-litre V10 engines of the early noughties had fuel-flow rates of more than 190kg/hr – so they were burning an awful lot more ‘juice’ to produce their grunt.
I would think that ICE automobiles would benefit by using electric motors in conjunction to the engine (hybrid technology as used in F1 trickled down to automakers). By the way, Honda is one of the automobile manufacturers that is involved in the F1 hybrid technology above. This company has been involved in F1 and Indi racing several years already.
The 2021 MB E450 has a turbocharged inline-six with both a mild hybrid system and an electric supercharger. The mild-hybrid makes a comprehensive stop-start system that begins rolling the car from a stop. The electric supercharger works at low RPM while the turbocharger is still building up compression. The inline-six engine only has one turbocharger which is a reach to the rear cylinders. But the 2022 MB E450 only notes the mild-hybrid system.
In general a mild-hybrid system should only be used to roll from a stop and then never wipe-out. Then a full hybrid system should only be used as an assisting system, which allows a smaller ICE, and then never wipe-out. However, 007 wants a hybrid system that allows an all-electric range but 007 often wipes out
.
I avoid using brakes. I picture burning dollar bills every time I touch the brake pedal.
Please register to post and access all features of our very popular forum. It is free and quick. Over $68,000 in prizes has already been given out to active posters on our forum. Additional giveaways are planned.
Detailed information about all U.S. cities, counties, and zip codes on our site: City-data.com.
Please register to participate in our discussions with 2 million other members - it's free and quick! Some forums can only be seen by registered members. After you create your account, you'll be able to customize options and access all our 15,000 new posts/day with fewer ads.
With apologies to the traffic behind me
