Review: 2024 BMW M340i xDrive – Jack of All Trades

There are a few ways you can evaluate greatness. One way is to showcase the best attributes of something within a given design. Another way is to examine how any downsides were mitigated to achieve greatness. So, what do you call something that achieves greatness in nearly every measurable metric and more? What do you call a car that does that? You call it the 2024 BMW M340i xDrive.

I spent ten days with this car and over a thousand miles, getting to know it very well. I’ve spent time in the 330e and 330i of this generation, so getting the chance to finally drive the M Performance model was a treat. The modern G20 generation of the 3 Series has been out now since its unveiling at the Paris Motor Show in 2018. In 2022, it received its Life Cycle Impulse (LCI) refresh. The chassis remains the same, but the LCI brought about new exterior styling, some updated packaging and options changes, as well as most notably, the iDrive 8 infotainment system and screen setup in the interior.

Nearly As Large As The E39 5 Series

The G20 BMW 3 Series has been praised for several of its best attributes, namely its chassis, great ride, and updated infotainment technology. Overall, the car has grown and is now actually less than two inches shorter than the E39 generation of the five series. The car is larger, but with that comes extra rear legroom and trunk space, which is now 17 cu ft. This is enough room to fit two large checked bags, a backpack, and three large duffle bags that just barely meet TSA compliance for overhead bin carry-on bags.

The G20 BMW M340i xDrive isn’t new, and the LCI has now been out for nearly two years. So why even bother talking about it? I felt this car doesn’t get the credit it deserves. Often, people ask, if you could only have one car, what would it be? Sometimes it’s hard to find an answer.

A Well-Rounded Car

Every car has tradeoffs. A lot of people might say they want a dedicated sports car for how fun they can be. But have you ever had to live with one day in and day out? It’s not always as fun as it seems in stop-and-go traffic and certainly not luxurious. You could get a nice luxury car, but then what if you enjoy a nice mountain road or a track day? It’s hard to find a car that can do all of that. The few that are capable of being this well-rounded usually come with exorbitant price tags.

There are other cars in this segment, but again, compromises. Each has them. The other two German cars are either much heavier, or understeer significantly, or come at a much higher price. The Japanese competition is either nearly 400lbs heavier, or ten years old. Value? Despite being the fastest sports sedan in the segment, the 2024 BMW M340i xDrive is not the most expensive at $59,600.

The Glorious B58 Engine

B58 in BMW M340i

The performance of the 2024 BMW M340i is impressive. This is largely due to its wonderful powertrain. The M340i is powered by a 3.0 liter inline-six turbocharged engine code-named B58. This engine has become incredibly popular for its power delivery, reliability, and fuel efficiency. The motor features a close-deck block and forged crankshaft for reliability and durability, and as such, the engine is understressed even while producing 382hp and 369 lb-ft of torque.

Tuners have been able to add over 600hp to this engine without many other modifications besides a software tune, but of course, that could affect the long-term reliability. It was proven to be such a great inline-six, Toyota opted to use this engine in their new Supra as a successor to the legendary 2JZ from the Mark IV Supra. 0 to 60 miles per hour hits in a claimed 4.1 seconds with the xDrive model, but some automotive publications have been able to achieve speeds below four seconds.

Mild Hybrid Now Integrated Within The Transmission

This engine in 2021 began to receive a mild hybrid system that is attached to the ZF 8-speed transmission. This mild hybrid system helps improve efficiency without much additional weight or complexity. While not a full hybrid system that can drive for any distance on electric only, it helps minimize fuel usage by allowing the engine to turn off whenever possible.

This is done in two different scenarios. The first is through turning off the engine at stop lights to prevent idling. While this isn’t new, the 48V system for this powertrain is incredibly quick to react and works seamlessly. The 12V systems in older stop-start systems can often be so rough and slow to react, they were often deactivated by their driver. With this system, there’s no need.

Impressive Fuel Economy

The most impressive means with which the mild hybrid system helps improve efficiency is by turning off the engine and allowing the car to coast while off throttle on the highway or approaching a stop light. A clutch pack disengages the engine from the transmission. What does this mean? Typically, when slowing down with a standard automatic transmission you may notice the car “engine braking” as the transmission, based on gearing, begins to slow the car down. With this decoupled, the car coasts with minimal speed loss from aerodynamic drag.

Overall, this mild hybrid system returns impressive fuel economy. The EPA rates the 2024 BMW M340i xDrive with 23 mpg city, 32 MPG highway, and 26 mpg combined. I was easily able to surpass this. Through several of my commutes around Los Angeles I was able to achieve anywhere from 37 to 41 MPG on highway driving. Overall, within 900 miles of driving I averaged 30 MPG. 30 MPG from a 382 hp car!

A Proper Sportscar Through The Canyons

This efficiency might be impressive in itself given its acceleration and power alone. That isn’t the only thing impressive about the car; it handles remarkably well too. I had the chance to drive the BMW M340i xDrive on some of Southern California’s best canyon roads that I’ve become very familiar with over the last several years. Despite this not being a full-fledged M car, it puts down a rapid pace. The 225-width front tires and 255-width rear tires may seem small given the power output, but the Michelin Pilot Sport 4S tires provided ample lateral grip.

The damper tuning on the M340i in Sport and Sport Plus modes is fairly stiff, but the rigidity of the chassis, in combination with excellent rebound and compression settings on the adjustable dampers, provided very competent and confidence-inspiring handling. The rear-biased xDrive does change the car’s overall handling at the limit when compared to the RWD model. While the RWD-only M340i can rotate wonderfully and provide some delightful oversteer when it’s wanted, the xDrive model has a slight hint of understeer. Though this makes the car feel stable under 9/10ths driving.

It’s up to you what driving characteristic you want, but I prefer the RWD model and feel. A small trade-off in acceleration gives not only better fuel economy but what I consider to be the ultimate job creator in driving: oversteer. If you were to add better pads, rotors, brake fluid, and coolant I have no doubt this can be used as a track car (as it is at BMW M Performance Driving Schools).

iDrive 8 Is Not Ideal

The interior of the G20 LCI 3 Series remains the same in the M340i as it is in the rest of the lineup. iDrive 8 dominates the interior with its large 15” central display and 12.3” driver’s display appearing as one curved unit. Sadly, we still lack physical HVAC controls but all other functions remain easy to use. Additionally, the display is both incredibly bright during the day and can be dimmed enough at night that it does not impair driving in dark areas. The Harmon Kardon sound system is fantastic for the price of just $875 in the United States. The only complaint may be the seats. They are comfortable enough, but they take some adjusting for them to feel ok which I can’t say about many other BMW products outside of the three series that have much more comfortable lumbar support.

Should I Buy One?

I loved my ten days I got to spend with the 2024 BMW M340i xDrive. This is a wonderful car. Normally I find some deep-rooted flaws or compromises that I would consider deal breakers. At the very least, I would find something that annoyed me enough to consider the competition. With this car, the breadth of capability mixed with the refinement and execution is something of brilliance. Nothing really bothered me about it to any great extent.

It was fun to drive on a backroad, comfortable and nice to live with on a daily basis, and still somehow, efficient. This car gives you 95% of the performance of the last F80 generation M3, mixed with 95% of the efficiency of the F30 330i. This car doesn’t have any noticeable downsides. It’s good at everything.

Is it maybe the best at any one thing? Maybe not. Is it one of the best buys for a one-car solution for the enthusiast? I would say so. This is everything BMW does best in one car: Performance, luxury, and practicality. If you have $65,000 and can only own one new car to do everything and still find the joy of driving, this is the car for you.