OP didn’t say “exotic”. You did.
Fiberglass’s strength is pretty much irrelevant since the body is not a load bearing structure. Steel’s strength is just as irrelevant, no?.
Ladies and Gentleman, the DeLorean. I cannot vouch for the frame, but the body is stainless steel with some fiberglass involved.
Would you buy an aluminum bodied Corolla if it cost $3000 more than a steel Corolla?
It would depend on:
Throw some numbers out: 10% weight reduction, 4% MPG increase (27.0–>28.1), 15K mi/year with gas at $3.50/gal (current dollars) over car life, and $500 scrap value increase after a 15 year life.
Crunching the numbers shows $80/yr savings ($1200 lifetime) + $500 scrap = $1700. So ,not worth it…but if the numbers were to change a bit, maybe, as it would have ancillary benefits of less rusting and better power/weight ratio (so I’d accept a modest monetary hit).
I’m also not sure how accurate any of the assumptions (yours or mine) are.
The driving forces in new car design are weight reduction, durability, and production costs. Fiberglass is too heavy for the required strength, also too expensive compared to steel. The slow production process and floor space requirements have been alluded to before.
John DeLorean’s car had a stainles steel body, but was expensive for a bread and butter production car. In the mid 50s a British company called Singer produced a family car with an all aluminum body. Again the cost was too high and they went out of business.
Steel (carbon steel) has remained the best option so far for car bodies, although many car components that used to be steel or copper are now extruded plastic, because it can compete with steel in that area.
The only other mass produced economy car I know of that did not have a steel body was the East German Trabant, which had a body made of vegetable-based plastic, the same stuff Henry Ford experimented with in 1945/46, using soybeans as a base. I don’t know the rationale for the Trabant’s body material (probaly local self-sufficiency), but East German economics did not follow the normal accepted practice.
P.S. In the late 50s and early 60s a French company, Panhard, produced a little 2 cylinder front drive car with an aluminum body, called the “Dyna”. It was light and streamlined, and very easy on gas, which was expensive in France at that time. It went out of production for the same reason, cost.
How do you keep a car rust free with maintenance? Especially in the north where the roads are often salted in the winter?
Washing your vehicle at once a week…and paying particular attention to the undercarriage can make a HUGE difference.
So the body remains rust free, while the frame/unibody rust away.
That’s a common problem with older Vets. I almost bought one 4 years ago (67 - 327) as a project car. The price was right…But the frame was completely rusted out. Would have to get a completely new frame…and I didn’t have the time for a complete restoration job.
Yes! The Trabant! I forgot about those! I don’t think they’d pass emissions requirements with their two-stroke engines though 
“Trabis” are becoming collector items in Germany (West) and there are several Trabi clubs. They were real 2 cycle smokers, and the owners want to remind themselves how even Germans under communism would produce awful products.
They are also painfully slow.
Aluminum: corrosion (basically equivalent of rusting). Generally, Al corrodes in a fashion that protects the underlying metal (passivation), but that is not always the case: Aluminum parts can and have corroded to the point of failure (Aloha Airlines). Assuming one wants to use Al in load-bearing parts (vs sheet metal only), you’re now talking about alloys of Al and other metals (6061, 7075, etc) that have different (generally worse) corrosion properties.
Carbon Fiber:
Fiberglass: Same problems as CF (except not expensive), with the added problem of not being light. Also, for both CF and 'glass, a very hot day could affect the structural integrity, depending on the properties of the resin used.
“I’m also not sure how accurate any of the assumptions (yours or mine) are.”
I don’t have the inside track on the cost of car bodies, but I do know that you have to get into the Audi A8 class before you get aluminum bodies. The A8 costs about $75,000 and up, so the price of the aluminum body isn’t a problem for a buyer. Most buyers look at the cost of the car up front and don’t consider the scrap cost, probably because most won’t keep the car until it’s scrapped. I do know that carbon fiber composites are often $1000/lb for the raw material alone. No wonder the car has to be a few hundred thousand to justify extensive use.
Try google Audi A2. Probably not sold in USA. Its all aluminum.
I’ll bet half if not more of all the questions we get about buying a used car with some age on, who describe the car they’re looking at as “mint”, NEVER crawled underneath, poked around the drain holes in the door and rocker panels or checked the rear quarters though the trunk trim, let alone a frame member itself. “Mint” suddenly disappears real fast when a screw driver pushes through a couple of inane bubbles in the paint. Ooops. Especially concerning when you realize that in a unibody, many of these areas are part of your frame as well and just as much a part of structural rigidity.
DeLoreans had stainless steel bodies, Caddy Allante were aluminum, as was the Honda Insight… Saturn, Fiero are plastic. They all look the same after they go through a shredder…
Your excuse: life is short. Enjoy every moment.
Just be sure you have either another vehicle for long drives or a very tough bottom. The seats have all the padding of a potholder. And the Elise has the suspension of a go-cart.
“Uhhh, that’s just ‘surface rust.’”
The Acura NSX also has an aluminum frame and body. First car with an all-aluminum monocoque body. Granted, it’s not an everyday car, but mid-90’s models (practically brand-new for a Honda!) sell for $20-30K.
You can buy new or rebuilt DeLoreans, which have a stainless steel chassis and SS body panels. When the company went bust, there were a lot of parts, and a guy bought them all up cheap. See www.delorean.com
Actually, an NSX can be an everyday car. It isn’t so exotic that it can’t be driven every day. I worked with a guy that drove his to work most of the time. He only drove his H1 when the weather was bad.
And I’ve seen people use them that way (nsxprime.com has lots of examples.) I would say it’s not “everyday” in the sense that there were only about 10,000 sent to North America over its entire production run (compared to ~30,000 Corvettes produced each year, or 400,000+ Camrys) but definitely “everyday” in terms of practicality. I remember seeing a picture of an NSX loaded with six big bags of fertilizer, for instance! It’s certainly got the driveability, and is definitely not so exotic that you can’t ever drive it - plenty of used ones sell today with 100K, 150K, and even 200K miles on them.
I believe this car is made of aluminum and wood. It shouldn’t rust.
You do not need a car made of aluminum, carbon fiber or plastic as in older Saturn to be able to keep it for a long time. I have a non rusting car and it’s made of steel. It is very old and is not driven on salted roads and therefore does not rust. Road salt is a car killer. Galvanized steel puts off the inevitable and road salt continues to attack brake parts, suspension parts and brake lines. Summer rain is not a problem for my old car.
If you want to keep a car forever, get a waste car to drive in winter in road salt regions and park the one that you want to keep.