We still aren't sure whether it will have a downsized bi/tri turbo V6 when the next generation of the high performance 3-series officially debuts, but as this video indicates—equipped with a V8 or not—the F80 M3 will still be quite fast.

According to GTspirit.com, this prototype was spotted on the German Autobahn in the vicinity of Braunschweig. Although this video was shot from the interior of a tuned BMW 1M with more than 420 horsepower, it certainly looks to us like keeping up with the new M3 at triple digit speeds was no small task.

The F80 M3 is expected to hit showrooms in the summer of 2013 as a 2014 model. Even if the engine is "downsized" we feel pretty safe guessing it will be more powerful than the 420 horsepower the current high revving V8 has to offer.

Sure the idea of a non inline six cylinder engine is a little weird, especially to vintage BMW lovers like ourselves. However, if the F80 M3 is truly a more powerful and improved version of the already excellent current model we're guessing one turn behind the wheel is all it will take to make our nostalgic reservations a thing of the past.

Remember that new 36-mpg 2012 BMW 3 Series we were so excited about, the 328i that got better fuel economy in EPA testing than even the old 335d diesel model? Well, those early estimates haven't held up.

BMW has confirmed to Autoblog that the EPA has issued revised numbers for the eight-speed automatic-equipped F30 328i, with highway fuel economy taking a 3-mile-per-gallon hit to 33 mpg and the city number dropping by a single digit to 23 mpg. BMW is investigating the discrepancy but says the 2012 figure will stay at 33. Spokesman Tom Plucinsky: "Unfortunately, there is no provision in the EPA rules for a re-test this year. Therefore regardless of the results of our investigation, the new rating will stand for this model year."

Though BMW says its testing showed the car capable of 36 mpg on the highway, the EPA decided to validate BMW's numbers and came away with different results. As we type this, the government's fueleconomy.gov website has not yet been updated, though BMW's consumer website reflects the new numbers. According to Plucinsky, buyers of the six-speed manual 328i can expect to see a 34 mpg highway figure on their window sticker, which fueleconomy.gov corroborates at 23/34.

What's surprising about this situation is that when we test drove the new 3 Series last fall, BMW told our Matt Davis it was estimating only 32 mpg highway. Plucinsky suggests that perhaps the 32-mpg figure was an "early estimate was based on the previous version of the 328i."

While the efficiency hit is disappointing, even with the downgrade to 33-to-34 miles per gallon, the 3 Series' fuel economy figures are still class-leading, besting competitors including the Acura TL and TSX, Audi A4, Cadillac CTS, Infiniti G, Lexus IS and Mercedes-Benz C-Class.

With all of that said, we can't help but wonder if this development will add fuel to the fire of those who have been clamoring for the EPA to "retest" the fuel economy of vehicles in the wake of owner complaints?

While the efficiency hit is disappointing, even with the downgrade to 33-to-34 miles per gallon, the 3 Series' fuel economy figures are still class-leading, besting competitors including the Acura TL and TSX, Audi A4, Cadillac CTS, Infiniti G, Lexus IS and Mercedes-Benz C-Class

There are no sacred cows when it comes to the BMW M3. Its first engine was a lightweight four-cylinder, then BMW bumped it up to a straight-6 and later to a small-displacement V8. It wasn't about adhering to some kind of long-forgotten company mandate, it was simply about which engine made the M3 better.

That kind of thinking could make the upcoming 2014 BMW M3 yet another ground-breaking new vehicle when it arrives in about two years. Although initial rumors pointed to the possibility of an inline-6 boosted by a trio of turbochargers, there's another, even more radical change in the works — a V6.

Because a V6 Fits
Yes, a highly advanced 3.0-liter twin-turbo V6 is being developed, according to a BMW insider. The rejection of an inline-6, it's claimed, is for reasons of packaging. The new V6 will be the first to mount its two twin-scroll turbochargers within the vee-angle, mirroring the company's 4.4-liter V8 design. This unique-to-BMW approach reduces the length of the inlet tract compared with a regular turbo-vee setup, helping to sharpen throttle response and minimizing heat buildup after air passes through the intercooler.

The V6 apparently won't be simply a cut-down version of the BMW V8, even though history records the M3's 4.0-liter V8 as a chopped version of the old M5 V10, with an identical bore and stroke. A two-cylinder cut of the 4,395cc V8 results in a 3,270cc capacity, yet our insider insists that a 3.0-liter capacity is most likely.

In theory, a 60-degree vee offers the best primary balance for a six; however, a 90-degree angle is required for the two turbos to fit. BMW must then solve the imbalance issue by using either balance shafts or a unique firing order, as it did with the 90-degree V10 in the E60 M5. Outputs of the unique-to-M3 engine are believed to be around 429 horsepower and 405 pound-feet of torque: sufficient to fend off the Audi RS4 and Mercedes C63 AMG. Improved direct injection, extra boost and a higher compression ratio will all contribute to the advantage the V6 will have over the BMW 1M's 3.0-liter twin-turbo straight-6.

For the first time, the M3 four-door sedan will launch before the two-door body styles.

So while the new twin-turbo V6 does seem the likely power source for the new M3, it also signals the end of a high-revving naturally aspirated engine for the car, a format synonymous with the badge over the past 26 years.

Shaving Pounds Where They Count
The next M3 will also be larger, yet lighter than the outgoing generation. Although the new F30 3 Series sedan is 3.7 inches longer than the E90, on average the range weighs 88 pounds less, thanks to alloy chassis components and increased use of ultra-high-tensile steel throughout the body. Further weight-loss strategies will be employed in the M3, with the M3 CRT concept previewing the advances.

Lightweight design components include a carbon honeycomb hood weighing around 6.6 pounds, titanium mufflers and carbon composite panels and seat parts. Aluminum wiring for the car's electronics replaces heavier copper, saving another 15-20 pounds overall.

BMW is reportedly working on carbon-ceramic discs and aluminum calipers — saving 33 pounds on each corner — but this expensive tech will likely be introduced late in the car's life cycle. Expect the M3 to tip the scales close to 3,483 pounds, which would be about 75 pounds less than the current coupe. Electric power steering — not fitted to the new M5 — is a possibility for the new M3, while a six-speed manual will continue alongside a revised seven-speed dual-clutch gearbox.

The E92's electronics — including adaptive dampers and M-Sport differential — will be revised to complement the new 3 Series' wider tracks.

The Internal Word
For the first time, the M3 will get a unique code name, tipped to be F80 for the sedan and F82 for the coupe and convertible. Also for the first time, the M3 four-door sedan will launch before the two-door body styles. Debate continues inside Munich over the possibility of renaming the 3 Series coupe and convertible as the 4 Series; however, a name change to M4 is something the M division is apparently actively against.

When the M3/M4 debuts in early 2014, it will need to comply with Euro 6 emissions standards and substantially undercut both the E92's 11.9L/100km and 1M's 9.6L/100km consumption ratings, while achieving a low-4-second 0-60-mph time. That's the new-age performance-car balancing act facing the M division engineers — more power and reduced emissions, all while maintaining crisp throttle response and high rev-ability. It's not easy, but when you are free to use any means possible, it sure makes things easier.