[q]Some years ago, I read an article by Amory Lovins of the Rocky Mountain Institute on Hypercars. It intrigued me at the time, as I was actively building EVs back then, but now I think there is perhaps even more added value in his words. Here is a link to the bulk of the text, even though it is not the original paper – I’ll have to get Googling to find this. He says that todays cars are too big and heavy, and they get fatter every year. For example a 1976 Ford Fiesta weighed 750kg (1650lbs) and now 25 years on the 2001 Fiesta weighs 950kg (2090lbs) and as such has to have a bigger engine,stronges suspension etc, etc. Amory Lovins said we should strip away all the junk from cars, and leave a lightweight vehicle, especially suited to the sort of 1 person commuter trips we all do these days. For an example, consider the power to weight ratio of a typical car 1200kg fitted with a 50kW engine. As a rough calculation that’s 1kW for every 24kg of the car body weight. Now if the car is only carrying 1 passenger, and the road speed seldom exceeds 45 to 50 mph on the commute journey, could you not reduce the size of the car considerably and match it closer to the weight of the driver. So instead of 1200kg car carrying a 100kg driver (+ luggage) you strip this right down to a 400kg car or better still 300kg car and scale the engine size down accordingly to maintain the power to weight ratio. So an all up weight of 400kg fitted with a 16kW engine. Same power to weight but a lot less metal to have to accelerate. Surprisingly enough, this approach takes us back to the 1920′ where little 2 seater cars like the Austin 7 weighed in at about 6.5 cwt (331kg) 730lbs and were powered by 8kW (10.5hp) engines. [/q]
[a]
And folded like an accordion in any kind of wreck, usually maiming their drivers. A lot of this “Added weight” is the mandated safety equipment built into cars today, air bags, telescoping steering columns (So the driver doesn’t get impaled in a wreck) “Crush Zones” ( A deliberate allowing of the body/frame/fenders to fold in a wreck, thereby absorbing the energy of collision) “safety cage” passenger compartments, (allowing the main body to resist collapse) stronger seats, “Hard Points” (To fasten things like seats, and seat belts so they won’t pull lose in a wreck) and such ideas as slanted firewalls that push the engine down and the body up to prevent the engine from sitting in your lap, (this also allows the inertia of the engine/transmission to be transferred away from the “Safety Cage” mentioned earlier) and a host of lesser ideas, such as not allowing any knobs to protrude at knee level, (they were great knee breaker/kneecap shatterers,) all good ideas that work to make cars much safer than those lightweight deathtraps of yesteryear.
But add weight. Which in itself is a good idea, they have found that the heavier the car/truck, the less injuries the driver/passengers sustain. So it’s all a compromise, safer cars mean heavier cars, fuel effency means lighter cars, “You pays your money, and you makes your choice”. that’s why there are so many pickups and SUV’s on the road today, the people have chosen safety over economy, (Don’t get me started on the Ford/Firestone fiasco)[/a]
[a]
Now your showing some age. I used to own a 37′ Austin 7. The real light weight ones were from memory the swift or swallow, a two convertible. Later on in the 50’s there were a whole bunch of strange shaped cars out of Europe. One door three wheeler types etc. Mostly the designs seemed to be driven by high cost of fuel etc. Your idea is a good one, given all the new high tech light weight materials available today. The design would be both light and strong, meeting the State and Federal codes for impact etc. [/a]
[a]
Perceived safety is always a good strong marketing point when you want to sell a punter the latest Detroit SUV, with its 3 litre V6 engine, 25mpg (best overall) and 3800lb body weight. The 2.8i Ford Galaxy (2001) model – manages a whopping 16.6 mpg on the urban fuel economy cycle. That figure is in UK gallons so is equivalent to 13.77 US mpg. The engine is capable of 204 hp (152kW) but you are hardly going to need that power driving to the office. Lightweight cars need not be unsafe, and it has been common practice in Formula 1 racing to make a very lightweight but immensely strong tub which protects the driver from even the worst collisions. Remember that the kinetic energy of a vehicle is directly probortional to its mass, so that a 1200kg car has to dissipate 3 times the collision energy of a vehicle weighing only 400kg. Lightweigt tubular steel could easily be used to great effect in producing an immensely stiff, low weight chassis. This is what Maseratti did back in the 1950s with their birdcage chassis. No way am I suggesting that we all drive around in quaint little wire wheeled, ash framed cars reminiscent of the 1920s, but with a little careful thought, and a radical approach to the vehicle chassis design, it is possible to dramatically reduce the vehicle weight without compromising the overall structural integrity of the passenger compartment. The AVT100 we built back in 1991, used 2″ ERW steel tubing for its chassis, forming a rigid steel endo-skeleton around the passenger compartment – a bit like the “roll cage” which is built into a modern rally car. This was then skinned in lightweight composite panels. The chassis was light enough for two of us to pick it up and carry it about the factory floor – about 200lbs. The AVT100, was however only half way towards the hypercar as a result of its electric traction and the need to carry 400kg of lead acid batteries. Despite this we had a vehicle which would travel 100km between charges and allow 85mph top speed – all this from a 20kw (27hp) peak rated electric motor – bought secondhand.
I believe that the motor manufacturing industry has run out of ideas, or they are too scared of bringing out a radical new design, just in case it is not as popular with customers. The long timescales, and massive investments in steel press tooling means that a new design is often 3 to 5 years in development, before it gets released on the public.
The Mercedes Swatch company have been particularly innovative on this front, coming up with a design where bodywork panels are plastic, non-structural and may easily be changed. if fashions change. The resulting vehicle – known as the “Smart Car” in Europe, is capable of 88mpg (73mpg US) and a top speed of 84mph – all in a package weighing 40% of the weight of the Ford Galaxy SUV. [/a]
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