Why are convertibles heavier than hardtops?
Whether you have been pouring over specs for the new Lamborghini Huracan Performante Spyder, or if you’ve just noticed that in general convertible models seem to be a bit heavier, we can help answer that lingering question. Why are convertibles heavier than hardtops? There are reasons, and we will dive into all of them.
What makes a convertible heavier?
You may be looking at that soft top of yours and wondering why the fixed hardtop version of the same car was actually lighter. The roof itself must surely be heavier on the hardtop, so why does cutting all that weight in the roof make your car heavier? To understand that you have to understand a little about the construction of a modern car.
Most cars these days are unibody, and that is doubly true for convertibles. This means there is no traditional frame. Instead, the body is the frame. When unibodies first became popular many people saw them as a bad thing, and that’s pretty silly actually.
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A unibody is a smart design for most automotive applications. Having a frame and a body is simply heavier, bulkier, and less efficient. Using a frame is like building a tree house and not using the tree for any support.
However, because it’s a unibody the structure of your vehicle relies heavily on the roof. Imagine crushing a closed cardboard box. Now crush the same box with the top open. It’s much easier the second time, isn’t it? To make up for the loss of a roof, engineers have to add a lot of weight to strengthen up the car. Hence why convertibles are heavier.
What about convertible hardtops?
All that structural stuff that we talked about previously is still in effect here because the car still has to be structurally sound when the roof is removed. Plus, you have to add in the weight for any mechanism that allows the roof to be removable. This is compounded even more if the vehicle uses a powered mechanism to fold the roof down.
In short, if the roof is removable you can expect the vehicle to be heavier. If this ever isn’t the case, then you are likely looking at a vehicle that was designed to be a convertible first and the fixed hardtop was an afterthought.