With the cold dense air, I am now getting 19 mpg average, which is abysmal in a 4 cylinder, especially when v6's easily get better. How's everyone else's milage going?

 

I've been on the upper 19s and thought the same myself.

 

I don't think winter in Ontario is very similar to Seattle, but poor winter mileage is normal here for a few reasons.

1) "Winter Gas" is at all the gas stations. It's purpose is to allow the gasoline to ignite more easily in cold conditions. It does reduce fuel economy. REFERENCE
2) People tend to start their cars and let them warm up for a period of time before driving away
3) People tend to keep the engine idling when parked, in order to keep the interior warm.
3) Driving through snow requires more power to overcome the rolling resistance

By the way, cold dense air actually improves the horsepower of an engine, because when it ignites, there are more air molecules expanding than there would be in warm ambient conditions. Since the engine control module maintains the fuel/air ratio the same, more gas is added to coincide with the additional air. But with more HP, there is less need to push the pedal down as far, so the effect on gas consumption due to cold air would seem to be negligible (in my humble opinion). Unless you drive like me and still stomp on the pedal to enjoy the extra horsepower available to me. This fact is why Cold Air Intakes (CAI's) are often added by driving enthusiasts,

 

My 2020 also gets terrible fuel economy in winter. 15 to 16L per 100 km right now. There's little doubt a small displacement V6 would be better without the fuel dilution issues.

 

Keep in mind too that our RDXs are still fairly heavy vehicles and that our turbo 4 puts out the same or higher horsepower & torque than a mid-sized 6 cylinder N/A (naturally aspirated) engine. Weight takes horsepower and torque to move and that takes fuel no matter how many cylinders the engine has.

I’m convinced our turbo fours are rarely more efficient than a comparable N/A six, but I also don’t think a six would return anything better on average either.

 

I'm getting about 10.8l/100km, or roughly 21 mpg. Majorly highway driven on this tank.
I've also been experimenting with normal/comfort modes. I notice that in Normal mode, the car definitely picks up quicker, but the acceleration from a dead stop is much harsher as well. This contributes to less fuel economy.

Additionally, when in comfort mode, although the car moves much slower from a dead stop (depending on pressure applied to pedal of course), I notice that once it engages 3rd gear pretty quickly and the speed in that gear is fast enough for regular city limits driving.
I've also noticed that the car tends to coast more in comfort mode, giving the car more rolling potential (similar to coasting in neutral). This attributes to better fuel economy in my opinion, since the car less frequently engine downshifts.

For reference, car is 2023 Aspec (Canadian). Engine is still being broken in though, only at ~1500km

 

Fuel consumption has risen

 

16.5 the best in City at average of 30F - it really sucks

 

I also suspect the aspec wheels are partly to blame. I read on here they are 34 pounds, and that's pretty damn heavy if you ask me. I live in a city, so the stop and go isn't doing any favors.

 

My experience with my RDX (and MDX too) is that winter weather saps 1-3 MPG.
However traffic congestion and stop and go driving makes the most difference by far.
In the cold north when we were in an urban area with stoplights every 1/2 to 1 mile, heavy traffic, and 30 MPH speeds the most we would see is 17-18 MPG.
Now down in southern Arizona with warmer weather, lighter traffic, stoplights 1-2 miles apart, and speeds of 45-50, we’re seeing 25-28 consistently.

 

Winter gas formulation, longer warm-up periods, colder more dense air (highway only) will all hurt fuel economy. As for the RDX, it seems the constant AWD system creates a lot of parasitic losses that hurts fuel economy, much more than what Acura advertises. Acura states the FWD model gets 22 city and 28 mpg highway. My FWD averages 27-28 mpg and gets 31-32 mpg at 74-76 mph. Acura states the AWD is rated just 1-mpg lower, (21/27) but that seems very wrong. Most AWD owners get 4-5 mpg less than EPA, if they’re lucky. I have no idea how Aura got away with misleading the AWD owners. The 2.0T engine is great. It’s the AWD system that hurts fuel economy.