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  • Miles Goodson

Running in a new car

The myths, the opinions, and the variety of thought when breaking in a new car

Running in a new car. Brand new car driving Speedometer
Running in a new car isn't just about the engine

Whether you call it breaking in a new car, running it in, or just choose go easy for the first few miles the method of driving a new car hasn't changed much. Ultimately, a new engine, suspension, body, interior, wheels and brakes among the many other parts have just been manufacturer and even in 2023 a new car needs a little extra care at first. The reality is that engineering has changed over the past few decades, and our understanding of metals has too, but that can't change the fact that even an electric car has lots of new parts that are still settling in to life on the road. The new car break in period can vary from handbook to handbook with the general guide being that the first 1,000 miles should be done without harsh acceleration or braking.


Do you still need to run in a new car?

Yes, mechanical engineering has come a long way, but it can't change the fact that the first time a brake pad touches a brake disc the two materials are 'bedding in'. The same for a combustion engine that spins metal parts against each other with oil for lubrication.


It's a picture many have seen when visiting a showroom filled with the newest and shiniest metal a manufacturer has to offer. Among the gleaming demonstrators, stock, and reserved vehicles there is someone stood next to a car in the collection zone with a brand new key in their hand and a salesman pointing to the fuel cap. Some chin-scratching, smiles, and today the inevitable tech fiddle as a phone is paired to the car for the first time so it can be driven home with all the customer's tunes playing at full volume in celebration of their purchase. The music choice is often more eclectic than the myriad of approaches people have to ask the question they almost forgot, 'do I need to run it in?".

Modern engineering and the easy finance/lease approach to vehicle replacement every few years leave many to simply get in and go, playing it safe for a few hundred miles and then not thinking any further about how high into the rev range they go. This group is now starting to ask a new question as to their option for propulsion grows, do they need to treat an electric car differently, does it need running in? We'll come onto that, first though let's sweep out the cobwebs of old knowledge and myths.


Do you need to run a car in?

Yes, Absolutely! Forget about the engine for a moment, brakes and tyres also need time and mileage to work at their optimum level. The disk and pad surfaces of the brakes need to form a clean pattern on their mating surface, there is a set procedure for this that race teams go through since they don't have hundreds of mileage to bed in the two materials, it is simply a case of heat build-up, steadily raising the temperature and then forcing the two surfaces together with greater friction until a peak heat point is reached and then backing off. For almost everyone on the road this process cannot be replicated, mainly because of the speed variations needed make it unsafe. Thus treating the brakes easy and avoiding hard depressions of the pedal at the beginning of each trip (unless it is needed for safety) is required for a few hundred miles. After that, you will have put the brakes through enough heat cycles that the disc and pad surfaces are bedded in correctly and a more spirited driving style can be adopted with a greatly reduced risk of warping or early brake fade. The tyres don't need any special procedure to wear them in, although braking traction on one side or from front to rear will cause uneven wear early and reduce their overall life. After fifty or so miles the compounds within the tyre will have been heat cycled and so again will give the best life and grip if they have been correctly worn up to this point. Other areas are suspension bushings and components. These are designed to live a tough life of constant movement, but it will take them some time to loosen up from brand new. Five hundred miles will usually have jiggled them in every way and moved about any fluids, rubbers, and other materials.

Run in engine

But what about the engine run-in?

So someone has told you all new cars are now designed to be driven hard from mile 1, another says that for the first 10,000 miles the car will be loosening up, and someone else has suggested avoiding certain rev ranges with incremental bumps the further you drive. The truth is that everyone here is both wrong and right. High-performance vehicles are usually quality controlled at the factory and ran at exceptionally high loads to make sure the customer of a £200,000 supercar doesn't make an angry phone call to the dealer a few days after picking the car up when they attend a track day. This is not something that a mid-spec Volkswagen Golf is tested for. The last stage of most new car production facilities is a vehicle performance run. The vehicle is filled with fluids and put onto a rolling road for a specified number of miles, driven at computer-controlled speeds, revolutions, and then given a full diagnostic check. This is what some people believe is the factory running the car in for the consumer, in fact, it is merely a quality control, making sure the vehicle performs within a letterbox of specified parameters for temperature, timing, fuel consumption, acceleration. Many high-performance vehicles will limit the very top of the rev range until a first service or mileage is hit, this is merely to protect the longevity of the engine. Can you drive a car hard from its first mile, yes, should you, no. Automotive engineers create motors that must operate in a very broad operating window, from the arctic circle of Finland to the deserts of Saudi Arabia. This makes modern engines very robust, but it doesn't mean you should take less care of them, simply put, they are still a bunch of spinning metal components with oil for lubrication, there is no magic here. So what about thousands of miles of running in? The theory comes from fact but is mostly misquoted. Combustion and compression engines will wear at a slightly higher rate when brand new, this is microscopic, but it follows the engineering. An engine has material that will be worn down due to use, it is why oil filters are needed as they filter the tiny shards of metal that are worn away with use. Initially, this wear will be ever so slightly higher than after thousands of miles as there is simply more material and it is more practical to overengineer the engine with a tolerance to operate with minuscule amounts of material missing than to try and perfect each component to within thousands of a micron. This is why people will quote an engine as 'loosening up' in the way it revs over time. Manufacturers attempt to optimise the process rather than aim for an arbitrary mileage target of five or ten thousand miles. The high figures are quoted because larger diesel engines that are designed to last for very high mileages may take much longer to wear the initial material due to the lack of stress they are exposed to in comparison with their overall output. Think of a truck engine that is designed to drive 500,000 miles in the most efficient way possible, it will take longer for this to reach the optimal zone of 'bedding in' or 'loosening up' simply because it has a lot of capacity that isn't used, lorries are speed restricted, and most companies will also have restrictions on driver inputs to optimise efficiency. You may also notice a difference after thousands of miles of driving, this is normal, but you shouldn't change your driving habits for months to accommodate it. Those that talk of incremental increases in engine load, for example, avoiding going above a certain rev range for the first thousand miles are usually quoting information given by some manufacturers. Other vehicles, the E92 BMW M3 a notable example, required an initial service at around 2,000 miles and the very top of the rev range is restricted from use until the car is taken back to the dealer for this service that then releases the car's full potential from the electronics. Similarly, manufacturers fit electronic cut-offs for many performance engines when they are cold, or don't allow the engine to be revved whilst stationary unless it is warm, the current generation Audi RS6 for example. All of this is to protect the engine and increases longevity, the higher the RPM of an engine, the faster everything is moving., the higher the wear rate. Some engines are designed better for this than others, Porsche expects their customers to spend a lot more time in the upper rev range of their vehicles than Skoda. This is what drives their development from the race track to find better, stronger, and more durable materials that not only perform better but more consistently over a higher wear rate. The idea of incrementally increasing engine speed isn't going to do any damage but it won't be as effective as simply taking care when the engine is cold, and then beginning to use a mix of high and low engine speeds.


The best method to run in a new car?

Engineering is forever developing, but some things simply don't change. Open up an engine from the 1950s and another from today and to the naked eye, there won't be a lot of differences. Metal, oil, and rubber with some plastic. Automotive engineers would see this as an oversimplification but it serves as a reminder to everyone that even with more computer control, advances in fuel, and leaps in engine materials the basics are the same. An engine just created will have slightly more material than one that has done 100,000 miles, it will also be much cleaner without the build-ups of carbon and other material that engineers expect over its lifetime. This means that treating all those components with consideration is important. Remember to allow the engine to warm up before using its potential, allow a thousand miles of different engine speeds whilst avoiding spending large amounts of time at the highest point of the rev band, this will ease the initial wear and should increase the overall longevity of the components. Also, avoid remaining away from anything other than very low engine speeds, the motor does need to be laboured a little otherwise the initial wear may be insignificant, meaning the running in and wear of the materials will take longer. If you must set a mileage limit then 1,000-1,500 is a good target. Crucially the first service should be carried out by the book, this is as important as running a vehicle in and if a car calls for an early first service or running in service then do so. If buying used and you see a first service has been extended long past its official recommendation or a running-in service wasn't carried out then tread carefully. Avoid driving a car hard from the first mile, yes the engineers considered this and the factory would have tested the car before it got a final sign off, but higher revolutions means higher temperatures, higher friction and higher rates of wear, when an engine is new it is going to wear a little more anyway, adding extra stress constantly is ill-advised. Drive the car normally but be aware of how you are driving it, shift early a few times, then allow it to rev higher and repeat. You don't need to regiment this attitude to every journey but keeping it in the back of your mind will help running in. If in any doubt remember that there is a large swathe of people out there that will just drive their car and ignore all running in advice, and you don't see them broken down every mile, modern engines are incredibly durable and their ability to function in a wide range of scenarios, being kind will only help, and if you are planning to keep the car long term you'll likely be rewarded with components that last longer, saving money and hassle in the long term.

Running in electric cars. Electric charging

What about electric cars, do they need running in?

Very little is spoken about the EV running in procedure but many things carry over from cars with engines. First off brakes still need bedding in, and in an electric car with regenerative braking the bedding in time for the discs and pads is likely to be longer as the discs and pads aren't used as much to slow the vehicle and thus the heat cycle needed to bed the materials in is happening at a slower rate. As a rule of thumb double the usual mileage you do to bed in a new set of brakes, the plus side is that EVs with regenerative braking generally wear their brakes much slower and so can go much longer between replacement. Next is the suspension. Many electric cars are much heavier than their petrol/diesel counterparts, meaning the suspension needs to be stronger. Due to this, it may take a little longer for the damping and bushings to wear in, however with the rise of SUVs in the last decade this is better understood and so the advice is similar, go easy and avoid pushing the handling characterises to their edge for the first few hundred miles.

Then there are the batteries, similar to an engine, batteries get hot, and they heat cycle with a cooling system, the main difference is how they create power. We talked about minuscule wear of metal parts in an engine. That won't happen with a battery, however, the charge/discharge rate will be optimum when new, and there are a few things you can do to maximise the longevity. Lithium batteries like to live between 20-80%. The best way to view the battery is as a sponge, a brand new sponge can soak up more water than an old one. How can you keep it soaking up as much energy as possible and reducing the rate of it discharges? Firstly, keeping the battery in the 20-80% charge zone, keeping it above this constantly will lead to a reduced overall capacity over time. Secondly, consider heat, if you live in a cold country or get your new car in winter, let that battery warm-up before asking for high throttle loads, in a hot climate make sure the battery is keeping cool, and any concerns should be reported to the dealer immediately. Lastly, the electric motors still spin and although they function differently from a combustion engine anything that moves, wears, so giving them a few hundred miles to get used to spinning around for a living to maximise optimum performance in the long term.


Do I really need to care?

Modern cars are able to take a lot more abuse than older ones, however, there is something to be said for considering how engineering has developed. For years cars were built with the idea that they should be made to last 'as long as possible' as getting them to their tenth birthday was a milestone. That era of engineering led to some truly astonishing machines that covered half a million miles and still run today. Think 90's Landcruisers and Mercedes W124. Now the concentration is on a life cycle. Engineers are not tasked with making a Ford Focus last for fifty years, instead, it is important that the cars operate efficiently to a planned obsolesce which should then have a high rate of reusable material to pull apart. If you want your car to last you'll need to be a participant in its overall care, otherwise expect it to last exactly as long as planned, for a typical car this is roughly twelve years, at which point it is assumed high-value items will fail, causing many owners to scrap the vehicle rather than fix it. The kindest environmental impact you can often have as a new car owner is giving a vehicle the best start in life possible to increase its service life, meaning less new parts need to be created to keep it on the road, and for those that enjoy driving for pleasure this means more miles with a smile than with a bill, it's win-win.


Note from Miles

Back when I sold new cars I always impressed upon people the idea that it wasn't just the engine they needed to think about when driving their new car. Most understood, others flippantly told me the car had been run in for them at the factory and although my advice was noted, it wasn't necessary so I was wasting my breath. Ultimately, they were the ones that usually had a part exchange that always needed work before it could be retailed, some with worryingly dangerous brakes. The best example of running in though was a sales manager who shall remain nameless. After receiving his new car, a hot model we rarely saw, he took it for what he called a '50 mile run in drive'. The smell when it returned is still chiseled into one of my nose hairs. It was as if someone had thrown molten and petrol up the exhaust pipe and lit a fuse. The car lived a hard life being the demonstrator for customers that wanted to test its performance, and it received no mercy from the sales manager. At 700 miles it went into the service centre for the first time for an unknown engine issue. Again it went it at 1,000 miles, then at 1,200 miles. A mechanic quietly told me that the oil filter had been changed twice, something had got too hot, and needed deep surgery to be fixed, oil changes were a sticking plaster repair, the general manager was not a happy bunny. The sales manger wasn't allowed another one after that. New cars need a little love too.



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