Most drivers would instinctively head to the nearest gas station to refill when the low fuel light comes alive. Letting your Bimmer’s tank go bone-dry will put you in an inconvenient situation — regardless of the location.

While it’s a given that an internal combustion engine vehicle with an empty tank won’t move, are there more consequences of ignoring the low fuel light? I pushed my Bimmer’s gas tank past “E” to know what would happen, and what I learned has made me a wiser BMW owner.

My Bimmer Ran for Dozens of Miles More

A BMW running on fumes can still run for tens of miles. That’s because the “E” in the fuel gauge actually means nearly empty, not absolutely empty.

A warning light will come on when your tank is 10%-15% below its capacity. For sedans, coupes and hatchbacks, it usually means you have 20-30 miles of range. If you drive an SUV or a pickup truck, you may stretch every drop of fuel left up to 50 miles. 

I heard a chime after my vehicle switched to the fuel reserve setting. After that, a distance-to-empty readout appeared on the dashboard — an approximate calculation of the mileage I could expect before my Bimmer would die on me.

The In-Dash Display Is Helpful — But Can Be Inaccurate

Thanks to advances in in-vehicle computers, the distance-to-empty figure is helpful. However, — although the figure takes multiple variables into account in real time — it makes assumptions based on historical data. Whatever happens next may drain your remaining gas more quickly.

For instance, driving more aggressively to quickly find a place to top off your tank can prove counterproductive and accelerate fuel consumption.

Hitting a curb is another example. This action can deflect a tire, compromising its structural integrity or causing it to lose air faster. A drop in tire pressure by 1 PSI reduces gas mileage by 0.2%, meaning an underinflation of 5 PSI renders your Bimmer 1% less efficient. Although it’s not astronomical, it’s big enough to move the needle closer to “E.”

Aside from roadworthiness, age and road conditions are vital factors affecting a vehicle’s fuel efficiency.

Consumer Reports tire program leader Ryan Pszczolkowski recommends cross-referencing your vehicle’s mpg against your in-dash fuel estimate to make a more realistic guess. I would agree with him because my prediction was closer to reality than my BMW’s distance-to-empty reading after factoring in my car’s recent mpg.

Most BMW enthusiasts — including myself — love Bimmers because they’re the epitome of German engineering excellence. However, we should balance common sense and faith in innovation. Modern auto technology only becomes more sophisticated over time, but it’s still fallible.

If you drive a 2023 BMW M2 coupe and remember that its highway mpg was 23, it’s probably less than that now. Note your mileage the next time you fill your tank to the brim.

Top up your tank, and set your trip odometer to zero before driving. When you return to a gas station, divide the amount of gas it takes to top up your tank by your trip counter’s reading. The answer reflects your Bimmer’s mpg at its age.

My Technician Found Signs of an Ailing Fuel Pump

It generally takes more than 100,000 miles before an average fuel pump fails. I haven’t covered that much distance with my Bimmer yet, but my BMW technician told me that my fuel pump looked prematurely worn out.

From what I gathered, driving on empty increases the risk of overheating. The small amount of gas can’t adequately lubricate and cool the fuel pump when driving. This component draws air in place of some of the gas, causing less fuel to move through the mechanism.

It didn’t help that my fuel filter is due for replacement. I normally change it at home every 20,000-30,000 miles, but it was apparently dirty enough to cause my fuel pump to suck up more sediment into the system. The little gas flowing through it while I was on the road with the low fuel light on was more concentrated, so it had to work harder.

I confessed what happened, and my technician advised me against pushing my luck the next time my BMW detects the gas level is low. Such a gamble could severely compromise my fuel pump, engine and catalytic converter.

I Learned My Lesson the Easy Way

Any Bimmer enthusiast knows that ignoring the low fuel warning light won’t lead to a happy ending. My experience satisfied my curiosity on some level, but I dodged a bullet. Quantifying the effects of driving on low fuel is challenging without making it a habit. Still, I nearly felt its impact on my pocket during my Bimmer’s annual full-car service at a dealership.

Make it a mission to refill as soon as your car begins to tap its fuel reserve to prolong its life and avoid hefty maintenance bills.