Jared Gall at Car and Driver has compiled a fantastic list of coupe vs. convertible weights and found that, on average, roughly 200 pounds is needed to give God a direct look into your car. But there’s hardly any consensus among different automakers.
Porsche, for example, has no difference in weight between its Cayman and Boxster, whereas BMW’s 4-series carries a 500-pound penalty for plein-air cruising. Many bespoke two-seaters carried small penalties for drop-top enthusiasts: Jaguar’s F-Type, Alfa Romeo’s 4C and Chevrolet Corvette convertibles were all only 1 to 2 percent heavier.
Fans of the C7 Covette may be interested to read this breakdown of the extra 90 lbs that the C7 Corvette has put on. For someone such as myself who is used to the OEMs brushing off weight gain or other uncomfortable facts with eye-roll inducing PR pap, the ‘Vette team deserves credit for this itemized breakdown of every component that added to the weight of the C7.
I have been a fan of TTAC for a while now. I am motivated to write by the recent responses to towing with a 2005 Odyssey. Two years ago I bought a 2008 Toyota Sienna and a 21 foot (actual total length) travel trailer. The trailer has a GVWR of 3500 lb, which the Sienna is rated to tow with its towing package. I had an independent shop install a fluid-to-air ATF cooler, unfortunately, perhaps, choosing the smallest model as it was recommended for a 3500 lb tow. I was concerned about getting too much cooling in the winter. The van already had an ATF cooler in the radiator. I had them put in an ATF temperature gauge (before the radiator) at the same time. The towed weight of the trailer is several hundred pounds below the GVWR, but it has a front profile that is basically vertical. I have towed the trailer about 20,000 km (yes, I’m in Canada) and done what Toyota calls an ATF change three times. That’s actually a drain the pan and refill with 4 L of ATF, not really a change. Of course, I have no way of knowing how accurate the gauge is, but the highest it’s been on the highway is 220 F on a couple of grades in the BC mountains (Coquihalla highway). The temperature went down as soon as the grade did. It went up to 240 F or so for a few minutes while backing up a steep hill and around a bit of a corner into a storage yard. The van had 38,000 km on it when purchased and is now at 82,000 km.
Enough background. I am writing to ask why it is apparently okay to tow a larger trailer (5000 lb rating) with a Highlander but not a 3500 lb trailer with a Sienna. As far as I can tell, the engine, transmission and weight of the vehicles are basically the same. The internet is rife with posters who advise against towing with a minivan but seem to have no qualms about doing so with a SUV, except the very smallest.
What do you think?
Thanks very much for helping me out with this. I can find no answer to my question on the internet. (Read More…)
The car industry is under pressure to improve fuel efficiency. It is not that they have been sitting on their thumbs. Automakers have achieved large increases in fuel efficiency through better technology in recent decades, says MIT economist Christopher Knittel.
The problem is:
“Most of that technological progress has gone into compensating for weight and horsepower.”
The theme that’s emerged most clearly from my interview with Bob Lutz was, somewhat counterintuitively, compromise. Every vehicle that’s developed and built is the product of nearly countless compromises, on everything from performance to efficiency, and from weight and materials to cost. The question isn’t so much if you compromise when developing a new car, but how you compromise… as was demonstrated in our last Lutzian anecdote. And even during my interview, as the conversation bounced from GM to Chrysler, from mass-market products to niche halo cars, I was thrilled that this issue kept coming up. Why? Because this theme played perfectly into the question that was at the top of my list of prepared questions. After all, there has been a mystery haunting GM followers for some time now… a mystery that I’d never seen a journalist ever ask about. And there I was, sitting with one of the few people who was even capable of fully answering it. So I just waited for a pause, opened my mouth and asked:
Why do GM cars weigh more than other cars?
I had no idea what kind of answer to expect… but I definitely wasn’t expecting the answer I got.
As automakers face slowly diminishing returns in their attempts to make internal combustion engines more efficient (while facing huge challenges in electric, hydrogen and other alt-fuel drivetrains), they are looking ever more closely at alternative materials to improve efficiency (and, to a lesser extent, driving pleasure) through weight-savings. Perhaps the biggest emerging trend in this area, especially at the higher end of the market, is in the use of carbon fiber, which is being actively pursued by automakers like BMW, Toyota, Lamborghini and Daimler. But, as WardsAuto points out, there’s another material that’s trying to earn a place in the lightweight cars of tomorrow: polycarbonate plastics.
Polycarbonate windows weigh half as much as glass, and because they are made with injection molding they can come in shapes that can’t be imagined with glass.
However, the material is more expensive. To get auto makers to convert, Sabic and its main material competitor, Bayer MaterialScience, have to sell the idea of integrating other parts into the plastic mold that makes the window.
For example, says Umamaheswara, “on a liftgate, a lot of features can be integrated, and if the manufacturer is short of room in the factory, it can be delivered as a module.”
A modular liftgate could include the window, cladding for the D-pillar, a roof spoiler, the high-mounted rear brake light, a rear wiper foot, handles and logos. When all those processing costs are included, he says, polycarbonate is competitive with glass and metal.
Yesterday we gave GM kudos for addressing its lingering vehicle weight issues by redesigning the head of its popular 3.6 liter V6, and shedding 13 lbs in the process. It was, we noted, the kind of news that showed GM is staying focused on the nitty-gritty of product development, sweating the details. But, according to a fascinating piece by GMInsideNews, new-product development at GM still has its issues. Specifically, Cadillac’s development of a new BMW 3-Series fighter, known as ATS after its “Alpha” Platform, has faced more than its fair share of what GMI calls “drama.”
Turf battles, unnecessary “wants” on checklists and ultimately a severe case of “Mission Creep” have created a vehicle that now needs a crash diet, according to GMI’s sources both within GM and at suppliers working on the Alpha/ATS program. For a vehicle that’s taking on an institution like the BMW Dreier (not to mention costing a billion dollars to develop), these are troubling signs indeed. (Read More…)
One of the most consistent and valid criticisms of GM’s product development, even in the post-Lutz era, is the class-leading weight that so many new GM products carry around with them. To a number of industry observers, the lingering weight problem that so many of GM’s cars struggle with is a sign of corners cut in the design process. GM’s cars may look, feel and drive better than they did five, let alone ten, years ago, but clearly the battle for truly “world class” products isn’t over.
And now we’re getting some of the first indications that GM is taking the weight issue seriously, as GreenCarCongress reports that GM’s engineers have pulled 13 lbs out of its 3.6 liter direct-injected V6 simply by redesigning its head. Given that the 3.6 is already one of GM’s better engines, and is used in a huge number of its vehicles, that’s a solid first step as The General takes on the battle of the bulge.
The Fisker Karma looks as sleek and and sexy as any four-door car on the market, but it’s got a secret: Spanx. Fisker’s powertrain sand battery suppliers tells the New York Times that prototypes of the series-hybrid Karma are weighing in at “over 5,000 lbs.” Says battery supplier A123 System’s Jason Forcier
It’s a pretty heavy car, but you have to look at all the technology, which includes a large gas engine, large electric motors and large batteries.
Fisker reps insist that the final product could come out weighing slightly less, but don’t hold your breath. Meanwhile the 50-mile EV range, 5.9 second 0-60 time and 125 mile top speed goals remain unchanged…. it will probably just feel lead-footed in the twisty stuff. On the other hand, by packaging its batteries in a low, central mass, Chevy’s Volt (the only other EREV on the market) actually handles fairly well for a nearly 4,000-lb compact. Still, “over 5,000 lbs” is full-sized SUV territory, and the Karma is being positioned as a green performance luxury car, not a chauffeured limo. Could this possibly end well?