Watch Your Car Weight – Is Heavier Always Worse?


When we buy a car, or when we are looking for a car, how often do we consider the weight? A vehicle’s weight can have a large impact on all aspects of its performance, and not always in the way that you would expect. Weight can be an advantage as well as a drawback, depending on the circumstances. Yes, I really said that: lighter is not always better. As a nation we have often been told to watch our weight, but what does this mean for cars? Worry not, for the answers are coming.

Before we begin, today is our last day of our 20% New Driver Discount for our car finder services. We can find you a car for less. We are still running our 10% Refer-A-Friends Offer as well. MotorKwirks will certainly look after you.

Weight is a killer. Or is it?
Weight is a killer. Or is it?

It’s well known that a heavier vehicle accelerates slower. All other things being equal, a heavier vehicle may also take longer to stop, although it may have more grip due to the higher weight, which counters this. However, weight does not actually affect the top speed, in theory. In practice, driving the same car with or without a heavy load will affect how hard the tyres are pressed against the road, and therefore their drag. But it certainly doesn’t have as much of an impact on top speed as some people might have thought.

Stability vs Agility
A heavier vehicle tends to be more stable. There is greater force pressing the vehicle onto the road and therefore one has more grip. But can’t that be mimicked by simply adding a few wings and spoilers, and increasing the downforce? Yes it can, but there are a couple of problems with this. Downforce levels depend on how fast the air is travelling over the vehicle. Thus both vehicle speed and wind speed affect downforce levels, and these change all the time. It also leaves the car maker with a bit of a dilemma. Do you set up the vehicle suspension and geometry for when it has maximum downforce, or minimum? Or somewhere in between? A vehicle that has greater stationary weight will likely be more stable under more circumstances.

Conversely, a lighter vehicle will have far less resistance to changes in direction. Anyone who driven a Caterham 7 will appreciate the undiluted joy of the light sportscar. There is far less inertia, so the car’s reactions are far more immediate, even when stepping out of a well sorted hot hatch. However, a heavier is not as easily destabilised, and so can be more easily handled on the limit. This all is very car dependent though.

So in an evasive manoeuvre, a lighter car may react more quickly, but a heavier will likely be more stable. Which is safer? As always, this is car dependent but to say that one is superior to the other is a bit too simplistic. Unless we are talking about SUVs, which are heavy, less agile and less stable than a normal car with a lower centre of gravity. Marginal and possible increases in passive safety at the cost of reduced active safety.

The tiny lip spoiler on this Golf GTi does pretty much nothing. Looks good though
The tiny lip spoiler on this Golf GTi does pretty much nothing. Looks good though

Component Wear
Increasing the weight of a vehicle will in most cases increase wear. Higher weight places more pressure on the suspension, and the transmission system has to work harder to shift a greater amount of mass. There is no doubt here that a lighter car will keep its components going for longer, and parts will not need replacing as often. And this is better for sustainability, which brings my nicely onto my final point…

All other aspects being equal, a lighter car is better for our environment. It requires less energy to enable it to move, and parts won’t need replacing as often. A lighter car pollutes less harmful gases in most cases. Much of the overall impact does depend on the manufacturing process, which fortunately more people are starting to take into account. It’s safe to say that if you are wanting to prolong the planet, and keep Sir Attenborough happy, buying a large 4X4 is probably not the best way to do it.

So for those of you that thought generally weight is bad for cars, you’re right. But the answer is not as simple as it may have first appeared. higher weight can be a big advantage in some situations. On the dual carriageway, I felt much safer on my big 1000cc motorbikes, than I did on my little 125 when the wind kept blowing me from lane to lane! The higher weight meant the larger tyres also had more grip so I could stop more quickly. Some of those advantages are applicable to some cars as well. If you after your ideal car, don’t forget to call us up, chat to us, and let us to the hard work. Thanks for reading!

What are your thoughts?