[marcedroid]

Hi everyone,

I'm new to the forum and hope you can help me with a concern I have regarding my 2016 BMW 420i Gran Coupe. I've noticed what seems to be an excessive fuel consumption issue, and I wanted to get some insights from the community.

Here's the situation:

• Vehicle: 2016 BMW 420i Gran Coupe
• Mileage: Approximately 53,000 km (33,000 miles)
• Current Fuel Consumption: Around 20L/100km
• Driving Conditions: Recent trip of 7km, 40 minutes, with an average speed of 11km/h

Last week, I noticed the fuel consumption was even worse, so I took the car to a mechanic. They replaced the thermostat, and while the fuel consumption has improved slightly, it still seems too high to me.

I’m trying to determine if this fuel consumption is normal given the driving conditions (short trip, low speed) or if there might be another underlying issue. Any insights or similar experiences would be greatly appreciated.

I’ve attached some photos for reference. Looking forward to hearing your thoughts and suggestions!

Thank you!

[Wires]

I wouldn't be trying to access fuel consumption on 7km trips, especially if they take 40 minutes. I'd take it out where you can get highway speeds if you want a better assessment.

[marcedroid]

Thanks Wires for your response. I live in a crowded city, and most of my trips are from home to work. I’ll try to take a longer trip this weekend to check the fuel consumption on longer trips.

[marcedroid]

This weekend, I took a slightly longer trip. It was about 20% city driving and 80% on a road with no traffic, with a maximum speed of 90 km/h due to speed regulations.

During the trip, the fuel consumption varied between 7.5 and 9 liters per 100 kilometers. In my opinion, this is a normal fuel consumption rate. However, fuel consumption in a crowded city with a lot of traffic is much higher!

I don't like the auto start-stop feature, so I disable it on every trip.

[Billfitz]

Fuel consumption in city driving of 10 miles per gallon isn't unusual. If there is a place where you want to use auto start/stop it's in the city. Fuel consumption while at a stop light is zero miles per gallon.

[marcedroid]

Billfitz thanks for your response. I've considered enabling the start-stop feature or switching to eco mode while driving in the city. However, I'm a little worried about the excessive use of the components every time the engine starts and stops after just a few seconds.

[Billfitz]

It doesn't seem to be a problem. Both the battery and starter are oversized for just that reason. It doesn't start and stop every few seconds, the car won't let it do that, to account for stop and go traffic. It won't let the battery go low either. If it was a cold start situation every time that could be problematic, but when the engine is warmed up the effort to restart is minimal. One place I wouldn't use Eco mode is the city, where you may need quicker acceleration.

[Wires]

Originally Posted by marcedroid

During the trip, the fuel consumption varied between 7.5 and 9 liters per 100 kilometers. In my opinion, this is a normal fuel consumption rate. However, fuel consumption in a crowded city with a lot of traffic is much higher!

I don't like the auto start-stop feature, so I disable it on every trip.

That sounds reasonable for mileage. In a full 100% highway at 110-120kph, I get 6.5-7.5 l/100km. Stop and go does consume a lot of fuel (you need to get a heavy mass moving).

I hate the start/stop as well. Mine remembers the start/stop setting so it stays off unless I bump the button above start. You can code this if your car doesn't remember the setting.

[marcedroid]

Originally Posted by Wires

That sounds reasonable for mileage. In a full 100% highway at 110-120kph, I get 6.5-7.5 l/100km. Stop and go does consume a lot of fuel (you need to get a heavy mass moving).

I hate the start/stop as well. Mine remembers the start/stop setting so it stays off unless I bump the button above start. You can code this if your car doesn't remember the setting.

Thanks! I think the fuel consumption is acceptable given the traffic conditions. I did the same with the start-stop feature on my car. During a maintenance visit, I asked the mechanic to enable the memory for the start-stop button.