Am I correct? Refuting my friend's claims that his bluetech is malfunctioning

[elias.taylorjq]

Someone I know owns a GL Bluetech approximately from 2009 or so. He claims to get about 15 mpg in the city. There has to be an issue with his car, in my opinion.

Just three pieces of information. 1) The 2005 E320 CDI that my roommate uses gets 30s city speeds 2) My 617, which is an engine from four decades ago, gets 23 mpg in the city, while my gasoline-powered Escalade, which is significantly larger in size and displacement, gets mid-16s with around 10% highway driving.

Weight, aerodynamics, and Atlanta traffic, in his opinion. Those, in my opinion, would have to be the deciding factors if the OM642 got slightly worse gas mileage than the OM648. From what I've seen, the EPA drastically underrates the efficiency of the E320 CDI. For example, I got 54mpg on the highway while driving it, but the EPA only gives it 27/37. What's more, my friend isn't even close to matching the EPA's estimate, which for the GL is 17/23. In my opinion, Mercedes will not swap out the 648 with a less efficient engine.

Benzworld, what is your opinion? Is my friend's SUV really only getting 15mpg on the oil burner GL, and isn't the 642 less fuel efficient than the 648?

[audreyqv]

Perhaps it's the way he drives.

[elias.taylorjq]

Most likely. There isn't much I can do to significantly alter the 617's city mileage, at least in my experience. No matter how I steer it, it stays in the low to mid-20s. I don't know if it's specific to diesels, 617s, or just my vehicle. I thought that effect would be present in diesels in general to a certain degree.

Further research revealed that the vehicle's real-world city economy is approximately 20mpg. As a result, he is 25% underweight.

[audreyqv]

After querying Google AI for owner ratings of actual driver efficiency, I received:
Minimal Gas Mileage: 16–18 MPG Fuel efficiency drops when driving frequently stops and starts. The diesel engine can't get up to its optimal operating temperature on short journeys.

"Mid 15" is, therefore, likely to be within the range of possibility.

[audreyqv]

When compared to diesels from the 1980s and 1990s, modern diesels are capable of far greater levels of performance. It gets good gas mileage when driven like an OM603, but it can burn through a lot more gas when used for stoplight racing.

Oh, and it's 2.5 tons heavy.

[elias.taylorjq]

Did you tell it to use its own training data or to go outside of its scope for research? Since the training data is only a snapshot in time, adding more data that it collects from research usually yields better results.

This 20mpg claim is now Claude's weak spot. While it did find data for mixed driving (22–24 mpg), it claims that the 20 mpg claim came from a handful of forum posts. Which is not as scientific as I would want.

[elias.taylorjq]

One advantage of AI is that it can be used for the following: "Is there a way to make sure this doesn't happen again? Is there a set of universal laws that you could adhere to without fail? Could you use any particular prompts that I might provide?

Hopefully, I have narrowed the focus a bit, but I am skeptical that the solutions it provided will actually fix the issue. Also, it's beneficial to gain a better understanding of the tool and its limitations.

[norajimeneztr]

In my opinion, 15 mpg is not good. The low to mid 20s seems like a reasonable estimate, though I don't put much city driving on my CDI. To be honest, I don't believe it when you say you got 54 mpg in your CDI. Personally, I'm lucky to get 36 mpg at most, and that's mostly on the highway: https://www.fuelly.com/car/mercedes-ben ... oh/1220063. (Please take note that I am well-versed in fuel economy as a driver; in my 2012 Volkswagen Golf TDI, which I honed with performance upgrades (my CDI merely has a tune), I achieved an average of 51.3 mpg over 130,000 miles (my best was around 59 mpg).

[norajimeneztr]

https://www.fuelly.com/car/mercedes-ben ... oh/1220063

[norajimeneztr]

https://www.fuelly.com/car/volkswagen/g ... hoh/333519