How come no other cars have Lean Burn

Lean burn has higher emissions, which is why it went away. The insight had a lean burn Atkinson engine. Diesel engines still do lean burn.

The insight has a smaller frontal area, making it more aerodynamic. That explains the highway mileage.

 

Specificly, it has higher NOx output. Even during the '90s and '80s, Honda had the leanest burning engines around. It was only possible through fine control of intake air flow. Among frugal hypermilers, the Civic VX is still prized. The aerocivic used a VX engine and transmission when it came time to replace them. Record mpg runs are mostly in lean burn Insights.

But only the federal versions are desired. California emission standards required the disabling of lean burn. The previous format of Fuel Economy allowed easy comparison between federal and Carb economy. Lean burn did have a big part to play in the Insight's highway fuel economy, since the engine only went into that mode during constant low loads.

With tightening federal standards and more states adopting Carb, lean burn has gone away in the US. It's still an option in some countries. It is still used in Australia. GM truck owners have used info from Holden to activate the lean burn subroutines in their ECMs to improve their economy.

 

I thought the current Insight, Civic Hybrid (2012) uses a lean burn engine? Maybe it doesn't. I believe the 6th Civics with lean burn (Civic HX trim) had 2 catalytic converters to keep emissions down but I could be wrong. I Heard that Honda stopped making a lean-burn option for the Civic because it got MPG so close to the hybrid, so they just made a lean-burn engine for the Hybrids. I can't verify any of that.

Yeah it's too bad lean-burn is not happening(?) with these new advanced engines. We could tap into a lot more MPG that way. Maybe if they develop catalytic convertes that can eliminate the NOX then it would be possible. Maybe a chemical exhaust treatment like Urea that is used on Diesels to cut down on NOX or particulats, I forget which.

 

Talk to your congressperson and get them to revise automobile emissions laws.

It's easy to get great fuel economy when you don't have to cater to overweight customers, the ongoing horsepower wars, virtually injury-free crash safety standards, and emissions levels so low the engine is practically cleaning the air. This is why the 1st-gen Insight will remain the fuel economy king for the foreseeable future.

Another big reason is cost. Making a lean-burn [and Diesel, FWIW] engine meet current emissions standards would add significant cost. This is one reason Diesel offerings are so much more money here in the 'States. Adding complicated after-treatment to a lean-burn Otto or Atkinson would add cost that very few would be willing to pay for. Adding $2k [just a rough guess] to the cost of a Prius C to make it emissions-compliant lean-burn would deter most, as it's over 10% the cost of the car. You can get away with a $2k bump on a $60k Mercedes-Benz, but most of those customers don't really care if their car gets 10% better fuel economy.

$0.02,
Ryan