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Mercedes-Benz engines with 48-volt systems coming in 2017

As part of a big green push announced yesterday, Mercedes-Benz is jumping into the world of 48-volt power. The company will launch a new family of efficient gasoline engines next year and will begin rolling out 48-volt systems with it, likely in its more expensive cars first. Mercedes will use the 48-volt systems to power mild-hybrid functions like energy recuperation (commonly called brake regeneration), engine stop-start, electric boost, and even moving a car from a stop on electric power alone. These features will be enabled through either an integrated starter-generator (Mercedes abbreviates it ISG) or a belt-driven generator (RSG). (RSG is from the German word for belt-driven generator, Riemenstartergeneratoren. That's your language lesson for the day.) Mercedes didn't offer many other details on the new family of engines. There are 48-volt systems already in production; Audi's three-compressor SQ7 engine uses an electric supercharger run by a 48-volt system, and there's a new SQ5 diesel on the horizon that will use a similar setup with the medium-voltage system. Electric superchargers require a lot of juice, which can be fed by either a supercapacitor or batteries in a 48-volt system. Why 48-volt Matters: Current hybrid and battery-electric vehicles make use of very high voltages in their batteries, motors, and the wiring that connects them, usually around 200 to 600 volts. The high voltage gives them enough power to move a big vehicle, but it also creates safety issues. The way to mitigate those safety issues is with added equipment, and that increases both cost and weight. You can see where this is going. By switching to a 48-volt system, the high-voltage issues go away and the electrical architecture benefits from four times the voltage of a normal vehicle system and uses the same current, providing four times the power. The electrical architecture will cost more than a 12-volt system but less than the complex and more dangerous systems in current electrified vehicles. The added cost makes sense now because automakers are running out of ways to wisely spend money for efficiency gains. Cars can retain a cheaper 12-volt battery for lower-power accessories and run the high-draw systems on the 48-volt circuit. The industry is moving toward 48-volt power, with the SAE working on a standard for the systems and Delphi claiming a 10-percent increase in fuel economy for cars that make the switch.

2019 BMW M850i xDrive: How it compares on paper with other GT coupes

Although the hot new vehicles for the rich seem to mainly comprise SUVs and supercars, the neglected luxury GT coupe segment is starting to see some life again. The latest to add a spark to this set is the 2019 BMW M850i xDrive. It goes on sale later this year, and revives the 8 Series that's been dead since the 1990s. The first version available to Americans will be one with a twin-turbo 4.4-liter V8, with other versions likely following. Before it launches, we wanted to get a lay of the grand-touring land and see how the new BMW stacks up to the competition in performance, practicality and price. While some of these models have higher-performance or more-affordable iterations, we picked the versions that would be the closest match to this 8 Series model. They include the 2019 Lexus LC 500, 2018 Mercedes-Benz SL 550, 2018 Mercedes-Benz S 560 Coupe and the 2018 Maserati GranTurismo. We will also provide some short summaries on our experiences with these cars, but to get a full picture of each model, be sure to check out their full reviews. And if you want to compare any of these cars with models you don't see here, be sure to try out our car comparison tool. Engines, transmissions and performance On paper, the BMW M850i xDrive is clearly the performer of the group. It has the most power and torque at 523 horsepower and 553 pound-feet. Coupled with all-wheel-drive and an eight-speed automatic, the car is able to overcome its relatively portly 4,478-pound curb weight to hit 60 mph in a scant 3.6 seconds. That's more than half a second quicker than the lightest car in the group, the Mercedes-Benz SL550, which weighs 4,012 pounds. The other three vehicles are in the low- to mid-4-second range to 60 mph. Though the Maserati is the slowest to 60 mph, it does boast the highest top speed of 186 mph. The M850i and SL 550 are electronically limited to 155 mph, while the Lexus is limited to 168 mph. The Mercedes S 560 has the lowest top speed at an electronically limited 130 mph. View 52 Photos Of interest is that there's a 50/50 split among these cars between using a pair of turbos, and having none at all. The BMW and Mercedes resort to forced induction, whereas the Lexus and Maserati choose to stay naturally aspirated. This is likely why the Germans break 500 pound-feet of torque, while the others don't make it to 400. Also interesting is the spread of gear quantity. The Maserati has just six ratios to choose from, and the Lexus has a whopping 10.

Submit your questions for Autoblog Podcast #325 LIVE!

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