Do speed bumps damage your car?

We’re supposed to be living in greener times. But speed bumps aren’t green, they encourage inefficient driving. Every time you use/apply a brake you are wasting fuel. There are one or two cars, like the Toyota Prius, that use regenerative braking – storing the potential energy in a battery – but they’re the exception not the rule.

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Smooth driving is the key to fuel economy and a healthy engine. If you think ahead, and drive at the appropriate speed for the conditions, you shouldn’t need to touch your brakes that often. All that speeding-up and slowing-down for speed humps, is just wasting fuel.

They also do harm to your car. The most common faults of hitting speed bumps too quickly are damage to the suspension parts and cracked sumps. What you’ve got to remember is that you get four knocks when you hit a bump at speed: the first impact when the front wheels hit and you get a bottoming-out, the knock to the suspension as it jolts upwards and then a second bottoming-out with the rear wheels and a subsequent knock.

A third of cars fail their MOTs because of damage to their suspension. I’d reckon most of that damage will come from hitting speed bumps, or misjudging the kerb when driving into a driveway.

Cracked sumps can be messy. The sump is a pan beneath the engine that stores the used oil before it’s pumped back into the engine. There are two types of sump: dry sumps are external. Crack this and you’ll drop oil around the place but it can easily be replaced. It’s not a big job but it’s not something you want to happen if you can avoid it.

A wet sump is actually in the bottom of the engine. Crack this and you’ll drop oil around the place and you’ve got a potentially expensive repair job.

You can fit rubbers to protect suspensions from damage caused by speed bumps but to be honest they’re a waste of money. My advice would be to take speed bumps as slowly as you can. If the road has a downhill gradient, coast in a low gear to save fuel. Much as I like getting work, it’s better for your car, and for your pocket, not to hit speed bumps in the first place.

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