Honda Insight Forum banner

1 - 12 of 12 Posts

·
Registered
Joined
·
605 Posts
Discussion Starter #1
Continue to check tire pressures monthly. The pressure will go down with increasing cold, and higher when it warms up, and a net loss over time as it gets colder, then warmer, then colder, then warmer…..

Use “S”, on the CVT, especially when accelerating from 0 mph, or hill climbing. This will increase engine rpm, and help the engine warm up faster (blue cold light goes out). Mpg is very very low when engine is cold. Normal spring through fall mpg in the high 40’s or 50’s requires a warm engine. It could take several miles to warm up. If your trip is short, you may have arrived at your destination when the system is ready to give you top mpg.

When the engine is cold you may notice that it wants to run at fast idle. If a way could be found to utilize that extra fuell/rpm, the mpg loss due to cold would not be as bad. Two things I do is:
1. Use “N” while sitting at traffic lights. The engine will free-run instead of pushing against the brakes, to hold the car still while getting the needed higher fast idle rpm . This means less fuel to achieve a given fast idle rpm. Resulting in a reduction of the mpg loss, while sitting at the traffic light. (“Normal” is auto-stop …no engine idle/fuel use at traffic lights.)

2. While driving a steady 15-30 mph with the cold light on, try taking your foot off of the gas pedal. The battery regen does not kick-in, the fuel used to insure fast idle rpm, can be used instead to maintain speed. At a steady 20 mph I see 15-25 mpg, on the instant mpg screen, with gentle gas pedal pressure. With my foot totally off of the gas pedal, I’ve seen instant mpg go up to around 40-60 mpg ! Of course when the engine warms, it all goes away, and battery regen returns and gentle gas pedal pressure is needed to maintain a steady speed.
 

·
Registered
Joined
·
1,102 Posts
When it is really cold it will rev higher in N while waiting at the lights than when in D - but it does not matter, it will recharge the battery faster that way, and still use less fuel.

I key off when I can. But again when it is cold it will take a few seconds before it reengages D after starting up, worse so if you rev it extra (it won't start in D so you have to start it in N) so only key off in the cold when you can start it 5 seconds before you need to move.

I run an UG and see it actually warms up pretty quickly, and gets excellent economy at 60 km/h or 40 mph after just a few miles. The pain is in the first few minutes; best to spend them driving instead of standing still with a running engine.
 

·
Registered
Joined
·
605 Posts
Discussion Starter #3
When it is really cold it will rev higher in N while waiting at the lights than when in D - but it does not matter, it will recharge the battery faster that way, and still use less fuel.
I noticed that the mpg goes down slower when in N than when in D. Besides it just makes more sense that you'd use less fuel running free than pushing against the brake pads.

Am not a technical expert, but I believe that the battery used to move the car is not charged by the engine, but only by the rotation of the wheels. It is the Prius that uses the engine, to charge the battery capable of moving the car. I believe the I2's engine does charge the small battery used for the electronics, heater, etc.

Thus N vs D does matter
 

·
Registered
Joined
·
1,102 Posts
Well, the Insight does not have a lump of steel for a flywheel, but a fully fledged electric motor/generator.
So yes it does charge in neutral. You have the generator bolted right to the crankshaft, no need to turn them wheels to put some juice in the battery.
After a while the revs go down, sure. I was referring to really cold, just started. I noticed it right this morning, it was what made me jump to your post.

It is not a Prius. It knows it is not a Prius. Prii know it's not a Prius. They tend to herd at my company's parking lot. They keep well away from that Red Devil Insight...
 

·
Registered
Joined
·
943 Posts
The engine must charge the battery rather than the wheels turning, or we wouldn't be able to use the stick it in P and rev it trick to charge the battery.
 

·
Registered
Joined
·
605 Posts
Discussion Starter #6
The engine must charge the battery rather than the wheels turning, or we wouldn't be able to use the stick it in P and rev it trick to charge the battery.
Am not familiar with your trick above, but do notice the movement of the chg-asst needle as I drive. When I first got the car I read what little tech info was available from Honda, but haven't kept up with it since. But there is no doubt that the majority of battery charging is from the wheels turning, unlike the evil Prius which will divert engine power to battery charging while driving.

Just try'n to figure some ways to squeeze-out a few more mpg's, on these very cold days, when people are getting mpg's in the high 30's.
 

·
Registered
Joined
·
943 Posts
Just to query the reasoning about using less fuel stopped in neutral than in D:

This would apply with a slushbox auto but I'm not so sure about the I2's CVT, which uses an automated clutch. In D, stopped with a foot on the brake pedal I believe that the clutch disengages - effectively the same as if you were in neutral.

By contrast being in D, foot off the brake with the hand brake / parking brake applied would use more fuel.

Having said that, Manuel Santos over at CleanMPG forum advocates switching to neutral for the Civic Hybrid CVT too. He seems very knowledgeable.

Just an additional note: in temperature ranges where the autostop will engage, switching to neutral with a foot on the brake sometimes engages the auto stop where it hadn't worked initially if slowing down in D.
 

·
Registered
Joined
·
1,102 Posts
Just to query the reasoning about using less fuel stopped in neutral than in D:

This would apply with a slushbox auto but I'm not so sure about the I2's CVT, which uses an automated clutch. In D, stopped with a foot on the brake pedal I believe that the clutch disengages - effectively the same as if you were in neutral.
I monitor instant fuel consumption on my UltraGauge. It does definitely use more fuel in D than in N with the foot brake engaged; about 50% more, but depends on whether the engine is warm or not.
So in N you use less fuel even if the revs are higher.
The auto clutch appears disengaged in N and engaged in D. I cannot move the car engine off in D. I can in N, easily.
EDIT Just tried - I actually CAN move the car in D, though it made a funny noise while doing so, like a spring scraping. It does not make scraping sounds in N.
 

·
Registered
Joined
·
943 Posts
So I wonder what's causing increased fuel usage in D? Could it be background charging the battery or something?

Edit: sorry -misread. I see you mean the clutch is engaged in D.
 

·
Registered
Joined
·
605 Posts
Discussion Starter #11
Yesterday I tried x4 to get some battery charging while stopped and in P. Failed all 4 times, at various battery charge levels. x2 during the forced regen phase. x1 with nearly full charge level. x1 at a low charge level but prior to forced regen. I slowly increased rpm to 2k ...nothing no charging. As I slowly reduced rpm there was about a second of charging. But not enough of a charge to be meaningful.

A 50% decrease in fuel flow in N vs D in a cold engine is significant when making short trips in very cold conditions. A warm engine, I would expect to use no fuel due to auto stop.

These small subtle things, are the difference I think, between tankfulls in the high 40's mpg vs 50+ mpg ..most of the year.
 

·
Premium Member
Joined
·
9,983 Posts
The people on echomodder beat this to death. Idling in drive vs neutral. They say the lower rpms in drive would mean less fuel over all injected in engine vs the higher rpms in neutral. Neutral is the winner.

Anyone check neutral vs park? :D
 
1 - 12 of 12 Posts
Top