The FR-S/BRZ loves the highway

[lordgrover]

Originally Posted by Tt3Sheppard

I think the mpg calculator in the car might be inaccurate. Car will say 33-35 average mpg. After doing a manual calculation it always brings me to around 30mpg. Thats with mostly 70-80mph highway driving.

Hmmm. I wonder if it takes into account the 'small' US gallon? A full imperial pint is 20 fl.oz. here.
35 mpg UK = 12.39km/l
35 mpg US = 14.88km/l

[sa1126]

I'm averaging 27.7 mpg and do all highway driving. Are you going by the calculated mpg or by calculating it on your own?

[gmookher]

Been spend ALOT of time up in the triple digits
27 ish

[elenien]

I averaged about 31mpg (calculated from my receipts) on my trip from Santa Barbara to Sacramento in my MT.

[Kundiethala]

Got a pretty good 34.6 mpg on my trip from Cleveland to NY. Granted I was only traveling round 65 mph the whole way but still I'll take it. Recently gave back a G37 coupe that avg 20 mph highway so anything above that is a plus.

[dori.]

Originally Posted by sa1126

I'm averaging 27.7 mpg and do all highway driving. Are you going by the calculated mpg or by calculating it on your own?

this is the BIG question. I don't entirely trust the car's calculation.

The computer said 30.2 avg and by my calcs it was 29.5

[Brimford]

Did a trip up to Chicago from Saint Louis, round trip i was doing 70-75 most of the way and I can confirm i was getting around 35 mpg with manual testing. Computer said i should have gotten 36-37.

[wrxgoose]

i can hyper-mile the mini (40-60 mpg on the highway) so i'm very interested in seeing what i can do in an FR-S

[FRiSson]

Recently, my car's mileage computer has been overreporting mpg by about 5%. I always double check by hand.

[Tt3Sheppard]

I'm thinking maybe the computer is overcompensating for idling with the a/c on/off. I see my mpg drop very quickly.

[raul]

Originally Posted by Tt3Sheppard

I think the mpg calculator in the car might be inaccurate. Car will say 33-35 average mpg. After doing a manual calculation it always brings me to around 30mpg. Thats with mostly 70-80mph highway driving.

3k at 80?? I think I get around 3800 almost 4k. I will have to double check this haha

My MT 86 does 86Mph at 3750 RPM.

[rice_classic]

I imagine that at cruising speed (highway) the best MPG's will be found at or below 3k rpms (aka: Before the tq dip). After 3k rpms in 6th gear you will face both a dip in power/tq and the obvious increase in wind resistance which will compound the negative ROI on MPG. The AT will cruise at a higher speed at 3k rpm than the MT so should be able to travel at a slightly great speed while in the optimal area of efficiency (power/speed/throttle/wind resistance) than the MT.

As for the trip calculator. I notice it is MOST accurate when I reset it after each fill up. It is usually within .5mpg of accuracy at every fill-up.

The one strange phenomenon I saw is that if I fill up next to the freeway, reset of the avg-calculator and hit the open road I can see 37-38mpgs. However, if I do the same thing but use the cruise control it only returns an average of 32-34mpg's on the read-out.

1: Either the cruise-control is less efficient than my right foot when on the freeway..

or

2: The avg-calculator and the cruise control don't get along too well.

[Propaganda]

For me, the average mpg calculator is pretty much spot on. On a 412 mile highway trip I took last week, I averaged 38mpg, with an average speed of ~70mph. This was also with changes in elevation, from right next to a river in PA to the mountains of southwestern VA. I didn't have to fill up my gas tank enroute, and I still had plenty of gas to go.

This was with a manual calculation, with a fill up right before getting on the highway and then right after getting off of it