Gas vs Electric · Head-to-head running cost
BMW i4 vs BMW 3 Series: what it really costs to run
The BMW i4 and the BMW 3 Series are essentially the same sport sedan in two fuel systems, so this page runs the i4's roughly 3.4 mi/kWh against the 3 Series' about 29 mpg in the calculator below, already set to both cars.
When you come out ahead
Showing cumulative fuel savings. Add the two cars' prices in the controls to plot your exact break-even point.
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A 3 Series in this class typically wants premium gas, and at about 29 mpg every mile is billed at a pump price you don't control. The i4 sidesteps that. At roughly 3.4 mi/kWh charged at home, its cost per mile lands well below what a premium-fed 3 Series runs, and there's no premium surcharge because electricity doesn't come in grades. The calculator shows the gap live for your own mileage and rates; the short version is that the i4 is the cheaper of the two to feed.
The catch is the sticker. The i4 starts around $52,000 versus roughly $45,000 for the 3 Series, so you carry a real up-front gap before per-mile savings start closing it. Because both are luxury sedans you'd want anyway, the i4's running-cost win reads more as a bonus than the reason to buy, and break-even stretches out. Lean on public DC fast-charging instead of home charging and the i4's per-mile edge over the 3 Series narrows, pushing that payback further out.
What to keep in mind
- The i4 skips premium-gas bills entirely, while the 3 Series' ~29 mpg is measured against pricier premium fuel, so the real pump gap is wider than the mpg number alone suggests.
- The i4 starts around $52,000 vs about $45,000 for the 3 Series, so plan on an up-front price gap that per-mile savings only chip away at slowly.
- At ~3.4 mi/kWh the i4 is cheap to run mainly if you charge at home; steady public fast-charging shrinks its edge over the 3 Series.
BMW i4 vs BMW 3 Series: common questions
Does the i4 really save money over a 3 Series if both are luxury cars?
On a per-mile basis, yes. The i4 at about 3.4 mi/kWh on home electricity costs noticeably less to feed than a ~29 mpg 3 Series running premium gas. But with the i4 starting around $52,000 against roughly $45,000 for the 3 Series, the running-cost savings are a bonus on the car you wanted, not a quick payback. Use the calculator to see where your break-even lands.
Will public charging cancel out the i4's advantage over the 3 Series?
It won't fully cancel it, but it narrows it a lot. Home charging is what makes the i4's ~3.4 mi/kWh so cheap; public DC fast-charging costs several times more per kWh. If most of your miles come from fast-chargers, the i4's edge over a ~29 mpg 3 Series shrinks toward break-even.