When is a quarter not a quarter? When it's on a modern car gas gauge. Why can't these things ever be accurate? Take my new MINI. On a full tank, it goes about 150 miles before it hits the 3/4 mark. It then goes another 100 miles or so before hitting the 1/2. Now that may be explainable by topping off although 50 miles difference seems a bit much. However, going from 1/2 to the 1/4 mark only gets about 70 miles. This is driving the same route, all interstate at 70 every day. My last car did exactly the same thing, so this isn't a MINI problem, it's a gas gauge problem in general. Why is it so difficult to make an accurate one?

 

Fuel sloshes.
It’s hard for an electro-mechanical device to measure a moving target.

 

I completely understand. I have the same problem and it drives me nuts sometimes. I'll get all excited that I went 300 miles on a half a tank and then 50 miles later I'm almost on empty.

 

Both my Minis, an Audi A6, a Camaro SS and a Honda Pralude did the same thing. I would get about 200 miles on the first half and only 100 miles on the second. Annoying as hell, but what are you going to do?

 

Excellent question - both of our MINIs follow the same trend regarding the extreme mileage for the first quarter tank. I know the first quarter tank will include excess from the filler neck but like you point out, the second quarter mark exceeds the next two by a wide margin also.

On another subject, where did you get the excellent MINI drawing from? I have checked the MINIs on cooperation's page and have never seen the V stripe except with the Checkmate package. Your representation looks like my HB/S (even the wheels match). TIA and hope someone has a good gas gauge explanation.

 

Could this be due to the shape of the fuel tank in the MINI? If I recall correctly, it is larger at the top than it is at the bottom, which would account for the readings you're getting. I would have thought the fuel gauge would have been electronically calibrated to take this account, but perhaps not...

Fuel sloshing will also account for inacuracies. The emptier the tank, the more the fuel will slosh around, the more inacurate the reading.

 

I've had the same problem with all my cars.
I just think of it as a logarithmic scale and it settles my mind.

 

My guess - Tanks are shaped to fit the space they are alloted. Odds are they aren't perfect rectangles, and likely narrow towards the bottom to: aid in fuel pickup and fit in between suspension members.

On the marketing side, people feel better when the guage doesn't move much after they've just spent $40 filling the tank.

Given that most MINIs have a 'Range' function, the gas gauge becomes less necessary.

Alternatively, the gas gauge was built by a frustrated calculus professor who wants to impress on drivers the concept of a variable decreasing at an increasing rate.

 

It actually was the Checkmate, but I took it into Photoshop, removed the checkmate graphics, and took the wheels from one of the other V-Spoke models to match my MINI. Took a little work, but it was worth it

 

yesterday, my brother was saying that this is happening in his wrx. so its deff. a problem with all cars.

 

It sure is. Years ago I got into the habit of setting the odometer on every fill up. It's a second look at how much fuel you have.

regards,
Red

 

yep, he was reading his odometer, too.

 

Exact same thing on my 06 MCS I get three times the amount of miles on the first half a tank then when i hit the half mile mark i might get 150 but ive gotten 400 from the top half of the tank

 

You're getting 550 miles on a tank in your MCS??

 

There was an article a year or so ago in "Car & Driver" entitled, "Is Your Fuel Guage Lying to You?" that went on to explain that the guages in almost all vehicles are designed to move slowly off of "Full" and accelerate toward "Empty" once the guage registers less than one-half.

 

Ooop typo, i meant 450 miles, thats one tank of all highway, like nonstop