In my previous car (Maxima), I always found the trip computer to be almost honest, but about 1.5 MPG on the optimistic side whenever I did my own consumption vs miles calculations.

Has anyone experimented to see how accurate the IS trip computer is? It sort of behooves a car maker to "round up" (hehe) and make the mileage look better than it is (because you'll report MPG to friends/family/coworkers/internet forums etc) , so I always compare it to my own math.

I don't take delivery of my IS until Monday so I can't really do it yet obviously.

 

I've always found it to be just a little optimistic. I would say around 2 - 3 mpg above average.

 

Mine is slightly optimistic. But not by much.

 

I test mine periodically and it's pretty accurate. Mine is never off more than 1-2 MPG.

 

Mine is about 1 to 1.5 MPG pessimistic. Calculated MPG has always been higher than the tank average.

 

1 - 2mpg here when i test it.

 

Optimistic?

 

My trip computer is around 2 mpg higher than what I calculate.

 

my actual MPG that i record is usually about 1.5 or so mpg less than what the car thinks.

 

Yup... sorry, should have said that

 

Mine is always 1-2 MPG lower than what I calculate.

 

Doesnt it depends on how you drive.. it will adjust itself if needed, correct me if im wrong

 

No, mine has been consistently around 1.5 MPG pessimistic since I got the car 4.5 years ago. There is some slight variability depending on how much you fill the tank after the pump stops (when doing the manual calculation), but over the long haul the error seems very consistent.

By the way, I think I must have the only IS where the trip computer reads a worse MPG than a manual calculation. It seems that practically everyone else sees the opposite.

 

Mine just told me I got 31 MPG driving between DC and Philly... considering it's an IS350, I think it is optimistic... but I do like seeing that number on there

If there's any truth to that number I'd be very excited... if I drove at a more reasonable pace I don't see why I couldn't squeeze another mile or two out of it.

 

It was exactly this accurate on my IS350: