# Miller Cycle Engines for Better Efficiency **URL:** \ **Category:** General Discussion\ **Created:** [January 30, 2011, 3:08pm UTC](https://community.cartalk.com/t/miller-cycle-engines-for-better-efficiency/60655 "2011-01-30T15:08:14Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![americar](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/americar/32/42_2.png) [@americar](https://community.cartalk.com/u/americar)\ **Post date:** [January 30, 2011, 3:08pm UTC](https://community.cartalk.com/t/miller-cycle-engines-for-better-efficiency/60655/1 "2011-01-30T15:08:14Z")
Hybrid vehicle such as the Prius use a Atkinsons Cycle engine which is a key component of the high gas mileage. If a Atkinsons engine is supercharger, it becomes a Miller Cycle engine. Does anybody remember the Mazda Millenia. So one would think auto manufactures would be jumping all over Miller Cycle Engine Technology for fuel efficiency. So Why Not? ---
**Author:** ![Joseph\_E\_Meehan](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/joseph_e_meehan/32/21_2.png) [@Joseph\_E\_Meehan](https://community.cartalk.com/u/Joseph_E_Meehan)\ **Post date:** [January 30, 2011, 3:26pm UTC](https://community.cartalk.com/t/miller-cycle-engines-for-better-efficiency/60655/2 "2011-01-30T15:26:14Z")
Just not worth the cost. ---
**Author:** ![B.L.E](https://avatars.discourse-cdn.com/v4/letter/b/848f3c/32.png) [@B.L.E](https://community.cartalk.com/u/B.L.E)\ **Post date:** [January 30, 2011, 4:03pm UTC](https://community.cartalk.com/t/miller-cycle-engines-for-better-efficiency/60655/3 "2011-01-30T16:03:54Z")
I think that the Atkinson cycle, which is a Miller cycle without the supercharger, is being used a lot more than you think. I believe that Toyota’s VVTi radically retards intake cam phasing during idle and cruise for lower pumping losses at part throttle and this effectively turns it into an Atkinson cycle engine. ---
**Author:** ![americar](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/americar/32/42_2.png) [@americar](https://community.cartalk.com/u/americar)\ **Post date:** [January 30, 2011, 4:21pm UTC](https://community.cartalk.com/t/miller-cycle-engines-for-better-efficiency/60655/4 "2011-01-30T16:21:34Z")
B.L.E, ``` That makes sense if VVT is able to adjust cam phasing such that it can go in and out of a Atkinson cycle, but I am unaware of any car manufacture marketing a engine of this type in any Vehicle. But I wouldn't be surprised if the Prius engine does something like that. ``` ---
**Author:** ![Caddyman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/caddyman/32/23_2.png) [@Caddyman](https://community.cartalk.com/u/Caddyman)\ **Post date:** [January 30, 2011, 7:09pm UTC](https://community.cartalk.com/t/miller-cycle-engines-for-better-efficiency/60655/5 "2011-01-30T19:09:05Z")
Like Joe said, the improvement is not worth the cost to achieve it…A much bigger gain can be had with lower cost by simply raising the operating temperature of the engine from 230 degrees to 300 degrees… People need to realize that 70% of the energy they buy as car fuel is used to heat the air around the vehicle, not propel it down the road… ---
**Author:** ![americar](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/americar/32/42_2.png) [@americar](https://community.cartalk.com/u/americar)\ **Post date:** [January 30, 2011, 8:38pm UTC](https://community.cartalk.com/t/miller-cycle-engines-for-better-efficiency/60655/6 "2011-01-30T20:38:53Z")
“People need to realize that 70% of the energy they buy as car fuel is used to heat the air around the vehicle, not propel it down the road”… That is nice know for those that live in cold or hot climates, and want to be comfortable while driving,and that turning on the heat and defroster, or A/C for that matter on a gasoline engine will not have a significant impact on the driving range or MPG of the vehicle because it was wasted energy anyway. On a Electric vehicle totally different story.