Image: Kyle PatrickImage: Kyle PatrickIt's no secret the next 3 Series is going to look quite a bit different. BMW has already shown off the all-electric i3, and if the brand's recent moves are any indication, the gas-powered model should look all but identical. After all, that's BMW's game plan: offer folks essentially the same car, but with a choice of powertrains. It's the case for the 5 and 7 Series.That presents a particular dilemma for fans of the current 3 Series-as well as the 4. Currently, on our side of the pond anyway, there is no electric 3 Series, only the 4 Series Gran Coupe in i4 form.AdvertisementAdvertisementWhile BMW hasn't confirmed what the 4 Series' future holds, it's safe to say the two examples here could be the last of their respective kinds of sport sedans. On the combustion side sits the M340i, here in commemorative 50 Jahre Edition. The plug-n-play side has the i4 M60, the global best-selling M-badged model. Time for a sibling rivalry.BMW i4 M60: All The DetailsBMW i4 M60: All The DetailsView Gallery28 photosCredit: Kyle PatrickHow Are They Similar?The 4 Series Gran Coupe is the four-door version of the two-door version (4 Series) of the four-door car (3 Series).Okay, it is a liftback and thus technically a five-door, but let us have the joke. Both vehicles ride on the same CLAR platform, have the same 112.2-inch (2,851-millimeter) wheelbase, and the interior measurements are broadly similar. The i4 is very slightly longer and taller than its traditional sibling.AdvertisementAdvertisementBoth models have all-wheel drive, though how they operate is quite a bit different, as the i4 has no physical connection between the axles.Looking forward from the driver's seat, these two are, surprise surprise, all but identical. The dashboard design is shared between both Bimmers, as is the center console. The door panels are different, however, with the higher-number model getting higher-mounted door pulls, aligned with the air vents on the dash. Armrest controls also migrate further down.BMW M340i: All The DetailsBMW M340i: All The DetailsView Gallery29 photosCredit: Kyle PatrickHow Are They Different?Obviously, the biggest difference is what powers these two. The M340i uses one of the myriad versions of BMW's venerable, turbocharged 3.0-liter inline-six. Here it makes a stout 386 horsepower and 398 pound-feet of torque. Like nearly every gas-powered 3 (and 4) Series, this one routes that power through a tried-and-true eight-speed automatic. Only the base M3 and M4 still offer manual transmissions.AdvertisementAdvertisementIf you want bigger numbers, the i4 M60 is the choice. 593 ponies and 586 lb-ft of torque are figures not far removed from the M5 of a decade ago, and the most power you'll find in BMWs this size.The M340i is super-quick for a "diet" M car, officially clocking 62 mph (100 km/h) from a standstill in just 4.3 seconds. Yet the i4 positively demolishes that with a 3.7-second run. In the real world, both stats feel conservative, too. These things are quick.Image: Kyle PatrickImage: Kyle PatrickFans of the classic sport sedan experience will appreciate the M340i. While it's one of the oldest options in the class now, it maintains a traditional balance that is easy to love. The xDrive all-wheel drive system will send power to the front axle when necessary, but there is a distinctly rear-biased feel to how the 3 tackles corners. While the suspension and throttle response tighten up nicely in sport mode (without being too extreme for daily driving), dialing everything down to softer settings allows the M340i's luxury side to shine. The engine burbles away while road and wind noise are minimal.AdvertisementAdvertisementThe i4 is both louder and quieter than the 3 Series. Naturally, it can be quite hush-hush so long as you don't turn on the Hans Zimmer-led artificial soundtrack. The frameless windows and liftback do allow for more outside noise to make its way into the cabin, mind you.There is a certain efficiency to how the i4 dissects a road that is satisfying in its own way. Shift to B and the regenerative braking is quite aggressive, helping tuck the nose into tighter corners. At lower speeds the i4's substantial weight penalty is barely noticeable; in fact it almost feels lighter since the weight is focused both lower in the body and more centrally between the axles. It's at higher speeds that the i4 starts to exhibit just a bit of hesitation.Despite sharing a platform, there is a general difference in attitude as well. The i4 feels tuned for a slightly more reserved ride, with softer rebound and more cushion in the tire sidewalls. The M340i is meaner and stiffer-arguably, on those very pretty wheels, a little too stiff.Image: Kyle PatrickImage: Kyle PatrickWhich BMW is Right for You?This question requires a bit of honesty. What do you want out of your BMW? What does your typical daily use look like?AdvertisementAdvertisementIf regular big distances are part of your life, the EV may be a challenge. The i4 will happily cover over 250 miles (402 kilometers) even with bouts of fun included. Should you need to stop, the i4 is one of the quicker-charging vehicles out there, capable of taking in 200 kW, so a 10-to-80 percent recharge should take around half an hour. Those frameless windows make the Gran Coupe feel a little more special, while the liftback imbues it with additional practicality. This is, without a doubt, the more modern and forward-thinking choice. (My hot take is it's actually better-looking too-yes, big grille and all.)Fans of the old school will gravitate towards the M340i. Sure, both of these cars are questionably "compact" now, and the 50 Jahre package makes it ride too stiff, but there is clear DNA between this and the E36 of the mid-'90s. That inline-six is silky smooth and sonorous, and BMW has worked magic to make it surprisingly efficient for something pushing 400 hp. Official figures are 29 mpg (8.1 L/100 km) combined and those with lots of highway commutes will see substantially better numbers.We can't forget pricing either-though the special status of this 3 Series must be emphasized. In Canada the M340i 50 Jahre Edition comes in at $94,855 CAD (including destination), but that leaves precious few boxes to tick. Merino leather? Standard. Individual paint? Standard. M Sport Pro package and the larger brakes? Ditto. The only addition is the $2,000 CAD driver assistance package. The i4 M60 starts at a cool nine grand less, but factor in the excellent Wildberry Metallic ($5,000 CAD) and white merino leather ($5,900 CAD) and it's already above the gasser. This tester has another ten grand in options, bringing the total damage to $109,105 CAD.Image: Kyle PatrickImage: Kyle PatrickWhat's Next for BMW's Sedans?This is the big question. We know what the i3 will look like. If it drives like the lower and lighter iX3 that it essentially is, it should be another all-electric hit for BMW. The model we've seen so far is a non-M i350, which puts out 469 hp and 476 lb-ft. If there is a direct replacement for this i4 M60, expect the horsepower figure to start with a 6.AdvertisementAdvertisementAnd the gasser 3 Series? BMW accidentally confirmed an M350 earlier this year, which suggests at least a modest bump in power for the model meant to bridge the gap between regular models and the mighty M3. Whether it will look like the i3 is unknown: all the models that share a number currently do except the iX3, which has a completely different look to the X3.BMW has confirmed a Touring model of the new 3 will arrive some time after launch. There's been no word on coupes, convertibles, or Gran Coupes, which have traditionally all been the domain of the 4 Series. Rumors suggest the existing 4s will roll on for two or three years after the 3 and i3 launch, which ironically could make the 4 the old-school option this time next year.Become an AutoGuide insider. Get the latest from the automotive world first by subscribing to our newsletter here.