So in the next 4-6 months it's very likely my commute will become dramatically longer. 35 miles roundtrip to approx 105 miles roundtrip every day.
The BRZ makes a terrible commuter car so I'm either going to ditch for a nice new fuel efficient car, or buy an old beater and let it sit in the garage most of the time (but that seems dumb).
So my question, when equipped with the same drivetrain (2.5 with regenerative braking) why is the smaller Mazda 3 hatchback rated for less mpg than the Mazda 6? I would think the smaller, lighter car would do better than the 6.
The 6 has less total aero drag, maybe?
Check the gearing. I haven't driven a new 3, but when I drove the 6 it struck me as having very tall gearing.
I had the new mazda 3 as a rental recently and it does have very short gearing. It certainly made the little 4 cylinder feel very sporty. I was impressed with the torque availability across the rpm range.
I'd guess it's a combination of both...gearing and aero drag of a hatch. I had a new (as in I was the first person to drive it) 2016 Mazda 3 as a rental. Very impressed with the car, but 6th gear was too short IMO. Otherwise, I thought it was a great car.
BTW, my commute is 110 miles round trip, so I get what you're saying.
Weight loss helps acceleration and in-town fuel economy, but doesn't do much on the freeway. IIRC this was discussed here once before and the consensus was that the 6's length allowed it to have much slicker aero.
Hatchback shape doesn't have the best aero. I think that's probably the main difference. The 2015 2.0 Mazda 3 my father owns has pretty tall gears.
Makes sense on the aero making a larger difference on the highway then weight.
Once I get closer I'll have to go drive one. The ex-wife has a 2015 Mazda 6 with that setup, and even if it has tall gearing, it never felt to me like it was lacking because it didn't have a V6.
Where are you seeing your numbers?
From what I've seen the hatchback 3 with the 2.5 is rated: 32 city / 39 highway, or 31/37 (not sure why the two listings).
The sedan 3 with the 2.5 is 33/40 or 32/40. https://www.fueleconomy.gov/feg/bymodel/2016_Mazda_3.shtml
Meanwhile, the 6 gets 26 city/ 38 highway.
Both 2016 models.
Both 3s are going to get much better city mileage than the 6, while the sedan 3 will get better highway mileage, and the hatch 3 will get just less, or just more than the 6, depending on which number you go by.
Directly from the Mazda web site.
The 6 with the tech package (adds the regenerative braking that I mentioned in the original post) boosts it to 40 on the highway. The 3 hatch, with the same drivetrain 2.5 and regenerative braking is 39 on the highway.
It's the 2.0 3 Hatch that's rated at 40 hwy.
That's directly from the Mazda web site if you go look through numbers.