Straight answer:

As of 2025, fueling a BMW M340i will cost you roughly $65–$90 per full tank, depending on gas prices in your area and how much you’re pushing that turbocharged inline-6 engine.

Now, is it cheap? No.

But is it unreasonable for what this car delivers? Not even close.

Let’s break down the real-world cost of fueling the M340i—plus a few things you should definitely know if you’re thinking about buying, leasing, or renting this beast in a place like Los Angeles.

1. Let’s Talk Numbers: Fuel Tank Size, MPG & Cost

Here’s the hard data:

  • Fuel tank capacity: 15.6 gallons
  • Fuel type: Premium unleaded (91 octane or higher—no cutting corners)
  • Average gas price in LA (2025): $5.00–$5.75 per gallon
  • EPA-rated MPG:
    • City: ~23 mpg
    • Highway: ~32 mpg
    • Combined: ~26 mpg (if you drive like a human being)

 Average cost to fill up:

  • Low end (at $5.00/gal): ~$78
  • High end (at $5.75/gal): ~$89
  • Partial fills or mid-week top-offs: ~$35–$50

Pro tip: You’ll get better fuel economy if you stick to Comfort mode on the highway—but where’s the fun in that, right?

2. What Does That Look Like Monthly?

Let’s assume a typical monthly mileage of 1,000 miles (commuting + weekend fun). Here’s a rough breakdown:

  • At 26 mpg, you’ll burn through about 38.5 gallons/month
  • Multiply that by the average gas price:
    • At $5.00/gal → ~$192/month
    • At $5.75/gal → ~$221/month

 If you’re pushing it harder or doing more city driving, expect that number to go up to ~$250–$275/month.

3. Okay, But Is the M340i That Thirsty?

Honestly? Not really, for what it is.

The BMW M340i delivers 382 horsepower, 0–60 in 4.1 seconds, and still returns better fuel economy than many V6 or V8 sedans. That’s kind of its sweet spot: performance without ridiculous running costs.

Compared to similarly powered competitors:

  • Audi S4: Similar MPG, slightly smaller tank
  • Mercedes-AMG C43: Slightly worse mileage, similar power
  • Dodge Charger Scat Pack: Laughably worse fuel economy (and it feels it)

So yeah—the M340i is actually respectable at the pump.

4. Renting One in Los Angeles? Here’s What to Expect

If you’re looking to rent a BMW M340i in LA, chances are you won’t be worrying about gas mileage—you’ll be too busy enjoying the way this thing handles Mulholland.

But still, here’s what to expect:

  • You’ll probably return it with a full tank
  • Rental services like Premier Auto Los Angeles recommend using premium fuel only
  • One full tank during a weekend rental might cost around $80
  • For multi-day trips, plan around $25–$35/day in gas (unless you’re flooring it)

 If you’re budgeting for a luxury weekend? Add ~$100 for fuel and enjoy every drop.

5. How to Save a Bit on Fuel Without Killing the Vibe

Let’s be real—you don’t get an M340i to drive like your grandma. But here are a few tricks to keep things balanced:

  • Use Eco Pro mode for city commutes (if you can resist)
  • Coast downhill and use adaptive cruise on freeways
  • Avoid stop-and-go traffic when possible (that’s where it drinks most)
  • Don’t skimp on premium fuel—it’ll hurt performance and MPG
  • Check tire pressure regularly—yes, it makes a difference

You don’t have to drive slowly—just drive smart when you’re not in a rush.

FAQs

Does the BMW M340i require premium gas?

Yes, absolutely. It’s designed to run on 91 octane or higher. Using lower-grade fuel can reduce performance and harm the engine.

How much does it cost to fill up a BMW M340i?

In 2025, expect to spend around $78–$89 per full tank, depending on fuel prices in your area.

What’s the real MPG for the BMW M340i?

You’ll get about 26 mpg combined—a bit higher on the highway and lower in traffic or Sport mode.

Is the M340i fuel efficient for a performance car?

Yes. For nearly 400 horsepower and serious performance, the M340i is surprisingly efficient.

Can I rent a BMW M340i in Los Angeles?

Definitely, Premier Auto Los Angeles offers M340i rentals with delivery options and performance-ready specs.

Final Thought: The BMW M340i Isn’t Cheap to Fuel—But It’s Worth Every Drop

This isn’t the kind of car you measure in miles per gallon. You measure it in grins per gallon.

So sure, you’ll spend $80 to fill it up—but what you get in return?

Power, precision, poise—and the kind of drive that reminds you why you love cars in the first place.