Bye-bye BS4, Hello BS6

    The biggest emission change in a decade is upon us, and starting today, new cars will be substantially cleaner. But while the planet wins, does the car buyer lose out?

    Published On Apr 01, 2020 06:26:00 PM


    Bye-bye BS4, Hello BS6

    April 1 marks a new chapter in the automotive industry. It’s a deadline both the auto companies and oil companies have been racing against time to meet. From today, only BS6 vehicles can be sold in the country (although the Supreme Court has allowed for BS4 cars to be sold and registered 10 days after the lockdown ends), and with this move to stricter emission standards, the face of the car market is set to change drastically. So what does this mean for the car buyer? Here are 6 things you should know:

    1) Cars have become cleaner  

    The most obvious change, and the very reason for moving to more stringent emissions norms, is that cars will be cleaner. Much cleaner. BS6 engines deliver a significant reduction in tailpipe emissions, especially in diesel cars. In a BS6 diesel, nasty pollutants like particulate matter (PM) and oxides of nitrogen (NOx) are reduced by 82 and 68 percent, respectively. In fact, the new BS6 emission standards literally give a clean chit to the vilified diesel engine. Petrol engines are cleaner too but the improvement isn’t as significant because they were less polluting in the BS4 stage.

    2) Cars have become more expensive

    Expensive hardware is needed for engines to lower their emission levels to meet BS6 standards and someone’s got to pay for it. A bit of the cost will be absorbed by the manufacturer but the bulk of it will be passed on to the car buyer. As a result, BS6 cars are more expensive than BS4 cars, especially the bigger diesels which practically have a laboratory on-board consisting of several exhaust treatment devices to clean up the pollutants. Petrols have it a lot easier and just need a larger catalytic converter to meet BS6. To soften the blow, many manufacturers quietly hiked the price of their BS4 models before the switch to BS6. A clever way to make you think the increase in prices of their BS6 models isn’t that high!

    3) Not all BS6 cars will be as efficient or drive as well as BS4... 

    This is true of most naturally aspirated petrol engines, as the bigger catalytic converter needed for BS6 comes with increased exhaust gas pressure which has a direct impact on driveability and efficiency. This loss could have been compensated with a higher octane rating as it would have allowed for a higher compression ratio. Oil companies, however, dropped the ball on this one and didn’t raise the octane rating of petrol to 95 as originally planned and stuck to 91 octane, the same as BS4 fuel. The low octane penalises fuel economy by as much as 3-4 percent. This is why the official fuel consumption on BS6 cars are lower than the same car with a BS4 engine. Also, as a result, the throttle response and power delivery in many BS6 cars have been dulled.

    4) … but some will drive better

    BS6 has ushered in the age of the small-displacement turbo-petrol, and, for many manufacturers that is a better solution than a large-capacity, naturally aspirated petrol engine in their quest to meet tightening emission norms. New-age direct-injection turbo-petrols offer an unbeatable mix of low emissions, good efficiency and strong performance. And it’s the performance that a turbo-petrol offers that completely transforms the way a car drives. Case in point is the way Hyundai’s 1.0 TGDI has elevated the driving experience of the humdrum Aura. Smooth, powerful, and with a strong mid-range to rival diesels, turbo-petrols are being positioned as an alternative to diesels, but are they?

    5) No substitute for diesel

    The high cost of meeting BS6 standards and the negative perception surrounding diesel has resulted in a diesel exodus. 17 diesel engines powering nearly 50 models have gone from the market, with no replacement planned. Car buyers will miss out on great engines like the Renault K9K, VW’s TDI, and, of course, the venerable Fiat 1.3 Multijet. The truth is, there is no substitute for diesel when it comes to sheer running costs, the huge torque that makes driving them a pleasure, and the phenomenal range and cruising ability which makes them great long-distance cars. It’s when a petrol car’s higher fuel consumption begins to bite that car owners will realise what they’ve lost.

    6) Fewer models and variants

    The ridiculously short time frame of just four years given to the industry to move from BS4 to BS6 has forced companies to prioritise which engines should be upgraded and which shouldn’t. As a result, many model variants with engines that didn’t make the move to BS6 have been given the axe. Maruti, VW and Renault, for example, have no diesel variants at all, while companies like Toyota have removed entire model lines (Corolla and Etios) as there was no business case for them to be upgraded. BS6 has also killed low-volume models like the Nissan Sunny and Micra, Honda’s BR-V, and the Fiat brand itself.

    Also see:

    BS6 norms special: part 1 – the background story

    BS6 norms special: part 2 – how BS6 engines work


    BS6 norms special: part 4 – BS6 and bikes

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