I recently took the trip to see my folks in the Myrtle Beach SC area which is about a 4 hour drive from Winston Salem NC. Now that my JCW Auto has over 2000 miles, I tried to see real world gas mileage over the highway. From my home after fillup at a gas station, in green mode, going mostly highway at 70-72mph with the top closed and A/C on set at 68 degrees, I managed 42.7 MPG from Winston Salem to Murrells Inlet SC. Doing the same trip in sport mode the whole way, same conditions, I managed 34.6 MPG. The trip is mainly flat as well. Still not bad, but nice to see a car capable of doing 153 MPH able to get this great of gas mileage with a flick of a switch.

 

Thanks for sharing. I'm assuming that you were more aggressive with the throttle [consciously or not] in Sport mode, as these cars are calibrated to run at Stoich for most operating band. Flipping a switch isn't going to change the AFRs especially at part load.

Are your numbers calculated or on-board computer? Cruise control the whole time? It's also tough to make a perfect comparison as your total elevation change was different going each way.

If you haven't done so yet, sign up for Fuelly to let everyone get a long-term perspective. I've been using it for a handful of cars now since 2010.

 

That's quite a difference, over 8 mpg just using Green mode. On the highway going fairly slow steady speeds I wonder how that can happen, assuming you're in 6th gear the whole time?

 

Mileage was calculated via the cars computer. I used cruise control the whole time. And yes, was in top gear. Elevation changes are fairly nill in variance because it's a pretty flat drive the whole way, except say crossing over the bridges near the beach. The biggest difference from keeping it in sport vs green seems to be that in green and in drive, it goes thru the gears faster to keep RPMs down versus in sport mode and sport transmission position, it keeps it in a lower gear and longer in gear for faster acceleration without need of down shifts. Plus I noticed the car appearing to coast a lot more, couldn't really hear the engine going.

 

This is a great post! Thanks Jet for sharing this info.

 

What's the average in green and sport mode for a day of city driving?

 

I'll have to try this out but it'll be a bit tough since around here, not much city driving, mainly highway or back country roads. On that note, I'm averaging around 29-31 mpg depending on my driving style per tank doing about 50 50 split in sport, and around 34 mpg using green mode for the same run to and from work. Gas mileage goes down to around 27ish if using manual shift mode throughout the week such as this week, but I'm also winding out the gears and accerlating hard in the back roads. Rev limiter comes up quite quick. And it's great fun to use launch control at stop lights.