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Remarkable strides have been made in both aerodynamics (reduce drag and noise) and engine efficiency. The glaringly missing factor is weight. Today's cars are heavy. Partially that's safety-regulations, partially consumer-preferences, and partially... who knows. If I were the efficiency-czar today, my emphasis would be on reducing vehicle weight.
Why can't we have a compact 4-seater sedan that weighs 1800 pounds?
The lighter the car, the smaller of an engine it needs, for the same acceleration. Smaller brakes. Smaller gas-tank. Lighter suspension-members. Smaller bearings, thinner subframe, and so on. Some safety-related factors don't necessarily scale down. Maybe the windshield can't be made thinner, or the seat-belt attachment points less sturdy. But most structural things and mechanical things scale down in symbiotic relationship, as overall mass decreases. That, I think, is the better route for less fuel-usage and lower emissions, all while retaining (or even increasing) performance!
At a guess, it's comfort and cost. My Insight weighed 1650lbs with the hybrid battery removed (it drives fine without it). A lot of the weight savings came from things like:
-Aluminum construction, was built next to the NSX supercar
-Lightweight 3 cylinder engine with light flywheel
-Manual transmission
-Alloy spare tire
-Exotic materials (e.g. magnesium oil pan)
-Seats made to be light above all else, no adjustment
-No adjustment in steering wheel
-Thinner plastics in the cabin, which tend to rattle
-No heavy balance shafts in the drivetrain, lots of vibrations
-No sound dampening on sheet metal
-No accoustic glass
-Lightweight stereo (poor sound quality)
-No backseats (also allows optimal roof slope for aerodynamics
-Small, narrow, lightweight wheels and tires
As a result, it can accelerate reasonably with a 60HP engine and get near 100mpg on the highway in optimal conditions.
I've added around 200lbs to mine to make it a comfortable and quiet vehicle, but it still has the safety features of a 20 year old car, and was expensive to build.
Safety requirements or crash tests different not less stringent.
Quote:
Originally Posted by MnM258
I don't think Euro crash tests are less stringent, just different. This article suggests that they are somewhat more stringent in some areas, somewhat less stringent in others, they focus more on safety for pedestrians for example.
There are plenty of high speed entrances to major roads in Europe too. The rate of auto accident deaths is actually lower in many (but not all) European countries compared with the US. Of course car design standards are not the only factor in that but also road design, driving habits etc play a role.
Safety requirements or crash tests different not less stringent. I agree with different. No malice intended thanks for the correction. How do I find the real data on the internal combustion engine efficiency for the last 40 year time line. Thanks
Safety requirements or crash tests different not less stringent. I agree with different. No malice intended thanks for the correction. How do I find the real data on the internal combustion engine efficiency for the last 40 year time line. Thanks
Find out who, if anyone, measures and publishes this info. My guess is that GM, Toyota etc. don't publish or share these things unless it serves their marketing, and the government doesn't force them, much like tire companies don't have to publish absolute measures of rolling resistance in the US. The data simply isn't available to the public.
I'm impressed by the fact that we have factory 400-700HP V8's that can idle smooth as a low-HP 4cyl, have excellent drivability, and get better gas mileage than V6's from a decade ago.
20 years ago, to get 700HP out of a v8 required extensive mods that resulted in poor drivability and reliability.
Cars with internal combustion engines that are getting 55 mpg are being driven below the speed limit on the freeway. How many people do you know have the discipline to drive 60 mph in a 70 mph zone?
Cars with internal combustion engines that are getting 55 mpg are being driven below the speed limit on the freeway. How many people do you know have the discipline to drive 60 mph in a 70 mph zone?
This is true, broadly speaking. Aerodynamic drag goes up with the cube of speed, making it hard to get good fuel economy when driving faster. Another part of the equation is that people simply didn't drive as fast in the past.
I get around 65mpg at 75mph in my Insight, but it's also a tiny, 2-seater, rattly, slow car with no creature comforts and the bare minimum in features.
I'm so old, I remember when Michael Jackson was black. I covered the hard cold start problem in my post.
I also had to synchronize 12 Weber barrels and double, dual point distributors on 'Ferraris & Lamborghinis by ear. I'll stand by my original contention: new electronics haven't made that big a difference compared to their cost & complexity (not to mention unpredictability)....Pretty easy and cheap to remove a clogged carb jet and blow the dirt out. How long does it take to R&R a fuel injector? Can you do that on the side of the road?
Never had to do anything to a fuel injector. Not once. That's in multiple cars from multiple makers since 1995.
Remarkable strides have been made in both aerodynamics (reduce drag and noise) and engine efficiency. The glaringly missing factor is weight. Today's cars are heavy. Partially that's safety-regulations, partially consumer-preferences, and partially... who knows. If I were the efficiency-czar today, my emphasis would be on reducing vehicle weight.
Why can't we have a compact 4-seater sedan that weighs 1800 pounds?
The lighter the car, the smaller of an engine it needs, for the same acceleration. Smaller brakes. Smaller gas-tank. Lighter suspension-members. Smaller bearings, thinner subframe, and so on. Some safety-related factors don't necessarily scale down. Maybe the windshield can't be made thinner, or the seat-belt attachment points less sturdy. But most structural things and mechanical things scale down in symbiotic relationship, as overall mass decreases. That, I think, is the better route for less fuel-usage and lower emissions, all while retaining (or even increasing) performance!
You are right but on all counts. The closest car to what you are describing is the GEO Metro in 1991 at a weight of 1620 lbs.
The MPG was 43/51 with a combined MPG of 46 mpg.
The closest car to that description today is the Mitsubishi Mirage weight 1973 lbs 41 MPG highway
So has the 353 lb weight difference between these two vehicles cost 20% in fuel economy, 30 years later with all the mentioned innovations on this thread?
Has anyone found that internal combustion engine efficiency data 40 year time line yet. Thank you for your responses.
As was mentioned, small city cars are the mainstay of most European manufacturers, the VW Golf had been the biggest selling car in Europe for a long time I think
But the Golf is now over 3000 pounds. The original was half as much. Small cars have their own appeal and cultural standing (or lack thereof). My query was more about the comparative lack of enthusiasm for radical redesign of larger and more capacious vehicles, building them more like airplanes and less like cars, thus perhaps finding radical savings in weight.
Quote:
Originally Posted by BostonMike7
I
20 years ago, to get 700HP out of a v8 required extensive mods that resulted in poor drivability and reliability.
This is quite true, but it should also be noted that while the 500 hp level can be breached by a large (yet still comparatively efficient) V8, forced-induction is generally required to go higher. The big leap in recent years has been making turbochargers and superchargers efficient, reliable, and almost impalpable to the driver. Turbos of 30 years ago were laggy, temperamental and unreliable.
Quote:
Originally Posted by EckyX
This is true, broadly speaking. Aerodynamic drag goes up with the cube of speed, making it hard to get good fuel economy when driving faster. ...
Drag force goes as the square of speed, but power is force times speed, so power-required does indeed go as the cube. So, in high-speed situations, low drag is more important than low weight. In city-situations, with lots of acceleration and deceleration, but moderate top-speeds, low weight is more important.
Manufacturers have done an admirable job with decreasing drag, thus keeping mileage decently good even at high speeds. They could do more, but styling, consumer acceptance and government regulations probably impede them. I am impressed how today a drag coefficient of 0.30 is nothing special, whereas 30 years ago, it would have been phenomenal. Sports cars of the 1970s often could only manage 0.45, because they had headlights in scoops, no attention to under-body flow, lots of drag from flow separation off of the rear windscreen, and so forth. Much of this has been cleaned up, perhaps at the cost of aesthetics. Still, there's more gains to be found, if we rework the basic paradigm of how to package 4 people (or only 2 people?) in a box on wheels.
Manufacturers have done an admirable job with decreasing drag, thus keeping mileage decently good even at high speeds. They could do more, but styling, consumer acceptance and government regulations probably impede them. I am impressed how today a drag coefficient of 0.30 is nothing special, whereas 30 years ago, it would have been phenomenal. Sports cars of the 1970s often could only manage 0.45, because they had headlights in scoops, no attention to under-body flow, lots of drag from flow separation off of the rear windscreen, and so forth. Much of this has been cleaned up, perhaps at the cost of aesthetics. Still, there's more gains to be found, if we rework the basic paradigm of how to package 4 people (or only 2 people?) in a box on wheels.
Just an FYI, most Hondas in the last 80's and early 90's had drag coefficients close to 0.30. I want to say the 1988 CRX was 0.29?
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Safety requirements or crash tests different not less stringent.
