Originally Posted by nwiTJdave
What weighs more, a 1950's all steel frame and body car or a newer car with a plastic and sheet metal body?
Google search 59 Bel Air Vs 09 Malibu.
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The Bel Air is somewhat heavier, but it's also a physically larger vehicle. The Malibu is barely a midsize sedan, whereas the Bel Air was a full-size sedan in its time, and larger than most modern cars. It's hardly an apt comparison.
It's also notable that most cars today have little in the way of plastic bodywork.
Cars are down from their enormous weights in the 50s, but they're up from their downward peak in the early 90s. Again, this is because of increasingly strict DOT regulations requiring various safety structures and devices. One regulation spells a lot of it out: there's a minimum airspace requirement between the engine and the hood of a car now. Because engines can only be made so short, the hood has to be raised to clear it by so much. Since the hood is now taller, the seat has to be raised to see over it. Since the seat is higher, the roof is raised so people can drive the thing without their heads poking out of the car. Now it's a very tall, weird-looking thing, so they stretch it a bit in length and width to make it look proportionate again. Then they put bigger wheels on so it looks like a proper-sized car instead of a behemoth on 15" wheels. All this makes the car heavier and it also presents a bigger frontal surface area, so a bigger engine and stronger transmission are required to move it, and those add weight. And then the EPA is pushing for tighter emissions and fuel economy rules, a la the CAFE act of 1975, so the left and right hands aren't talking to each other and the carmakers are in the crossfire.
Now, I'm all for improved safety, and my wallet really likes better fuel economy, so I'm okay with these laws. I'm just saying it's a big engineering challenge to make both of them congruous and cars today are heavier than 15 or 20 years ago because of these regulations. There's evidence we've hit the upper peak because cars are now shedding pounds again. If the Wrangler wants to lose weight, an independent front suspension might be a viable way to do it. A definite way to cut some weight would be to employ a unibody design. More plastic bodywork would also drop a few pounds. For that matter, a fixed roof and windshield would definitely weigh less than the current setup because they could provide chassis rigidity without needing further reinforcement. Dropping the tire size would make for a huge improvement in mass, and ditching the full-size spare on the back would also help.
Of course, Jeep isn't considering any of those. The only one that's even been hinted is the IFS. Even that isn't set in stone, or even at all evident of the brand's direction.