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If you've followed some of my rants over the past few years, you're keenly aware of my disdain of the trend of automotive weight gain over the years. I know the standard industry line about "safety regulations" and "improved NVH." I'll grant that the bar is constantly being set higher and higher both by consumer expectations and government regulations.
However, for whatever reason, it seems many automakers are reverting back to the old, lazy way of increasing safety and improving NVH. Namely, adding weight.
Case-in-point: the 2010 Buick LaCrosse and the 2010 Lexus RX 350. Now, General Motors may claim economy improvements on the new LaCrosse which, for the most part, is true. 2009 models attained 17/28 for the V6 model and 16/24 for the V8 Super model. The 2010 version achieves 18/27 for the 3.0L model and 17/26 for the 3.6L model. A V8 is no longer offered. So, for the base model, the fuel economy improvement is essentially a wash, whereas the upgrade engine shows a modest improvement of 1 mpg in the city, and 3 mpg on the highway.
You'd think, with dramatically smaller-displacement and higher-tech powertrains (direct-injection, 6-speed transmissions), the economy gains would be more dramatic. But if you take a look at the scales, it's apparent why the economy gains are not greater. Model-for-model, the weight gain is between 453 and 516 pounds. You call that progress? If GM were able to hold the line on weight, the economy gains from the new engines and powertrains would likely be much more significant. As it is now, it's like permanently hauling around two very well-fed American adult males in your car.
 Those of you import lovers ready to pick up your stones to cast at Detroit, take note. The new Lexus RX 350 SUV has also gained a substantial 420-470 pounds depending on model configuration. Economy figures are roughly equivalent to the 2009 models. But how much better could they be without the added weight?
Perhaps the engineers or platform managers are not being strict enough, or setting the bar high enough during new model development. Granted, it may not be realistic to expect a weight cut with every successive model, taking into account ever-stricter safety requirements and consumers' insatiable appetites for the latest gadgetry. A 50-100 pound gain would be understandable and acceptable. But a 400-500 pound gain just shows engineering laziness, or over-zealous bean-counters vetoing the use of higher-cost materials such as high-strength steel, aluminum, or composites.
Or maybe the government safety regulations have become needlessly draconian that substantial weight gains are inevitable. Yet aren't these largely the same people that are requiring a 35 mpg CAFE standard? Granted, the Department of Transportation and Environmental Protection Agency are separate departments. But the common denominator between the two is that they're staffed by individuals whose job is to regulate. Maybe a little inter-departmental communication to help reach a more reasonable middle ground to support both safety and efficiency is in order.
Although high fuel economy targets might be achievable in spite of the added bulk, would they not be more easily achievable without having to contend with such substantial weight increases? What it comes down to is prioritizing targets at the early stages of vehicle development. Either you spend the money on lighter-weight materials and structural engineering, or spend the money on more efficient powertrains. Ideally, it would be both. But it seems to me the money would be better spent on keeping weight in check, which would complement the new generation of high-efficiency powerplants. My advice for carmakers...Lighten up!
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