Mercedes-Benz built a banger of an engine with its high-strung turbocharged four-pot. It belts out over 400 horsepower in its highest trim, but the automaker didn't account for one thing: its V8-loving buyers, especially for AMG variants.Now, another about-face could be coming to another Mercedes-AMG sports car. And dare we say, it just might be a tragedy in this particular instance. More Big Changes To The Mercedes SL Mercedes-AMGAccording to the German outlet Auto Motor Sport, Mercedes will replace the wickedly quick turbo-four in the Mercedes-AMG SL43 with a straight-six for its 2027 refresh because... the four-pot does not meet Euro 7 emissions standards. Yes, you read that right, the report claims that Mercedes will replace the smaller engine with an engine with two extra cylinders because of emissions. It's important to note the report is unverified and doesn't quote a source. But Auto Motor Sport also points out that the current model is no longer available for configuration in Europe.The Mercedes SL has had to move with the times to survive as a sporty roadster in the 21st century. According to the report, the 3.0-liter inline-six mild-hybrid engine SL will be called SL53 and come standard with all-wheel drive. If all this comes true, then expect 449 hp and some serious grip off the line for the entry-level SL. But, the story doesn't end there.Traditionally, the Mercedes SL has been a rear-wheel-drive roadster. It has also traditionally had a big V8 engine option, and that should continue with the SL55 and SL63 switching from a twin-turbocharged 4.0-liter engine. However, if this all plays out, the SL55 and SL63 will switch from a cross-plane crank configuration to a more entertaining flat-plane crank design. That will give the SL55 537 hp and a monstrous 650 hp to the SL63.No mention is made of the Mercedes-AMG SL63 S E Performance plug-in hybrid with its V8 engine and electric motor combining to make 805 hp and 1,047 pound-feet of torque, but that's already a hybrid, so Mercedes may not need to mess with that until, well, it does. It may not be long before the SL63 S E Performance gets a bump to 850 hp, which is truly an excess of power for the SL. Emissions In Everyone's Favor Mercedes-AMG With emissions laws and technology maturing, along with the high availability of hybrid and all-electric power, this could be a fascinating moment in automotive history. Instead of the feared reduction in power for cars due to emissions strangling, we're hitting a point where the question of how much horsepower we need is an interesting one. This would be a bump for the SL43 from 416 hp to 449 while satisfying even more stringent emissions laws in Europe. In 2016, the 3.0-liter V6-powered SL made 329 hp and used an automatic engine stop-start system to help save fuel.The range-topping 4.7-liter V8 version of the SL made 429 hp in 2016 – 20 horsepower less than the upcoming entry-level straight-six mild hybrid. We're certainly down for hybrid straight-six engines replacing the current standard of the turbocharged four in base models. However, it's worth remembering that we are talking about a car here with a starting price over $100,000. The AMG SL43 Roadster is still showing on the Mercedes website as available and starts at $112,550.