Irony, more efficient car, more miles

When we got our first Prius, I noticed I was driving more miles. With half the fuel cost of our earlier car, I thought nothing of taking more trips and thus drove more miles.

Recently I replaced our first Prius with an even more efficient ride and my miles increased again. I especially noticed it this week when the new car (actually used) has been in the shop for warranty repairs and I had to revert to our 2010 Prius.

So this morning, the gas gauge went 'ping' and I'm on the remaining +100 miles in the tank. Didn't I fill up just a week or so ago? Actually that was just under 500 miles ago whereas I'm usually going +600 miles between fill-ups. One possibility is the new car is 'unlearning' the Prius tricks we use to maximize efficiency:

• Engine efficient acceleration - In the Prius, we accelerate trying to avoid going over 3,200 rpm to stay within the most efficient engine operating range. In contrast, new car has no such limitations. Rather the fixed vehicle overhead encourages accelerating a little faster to minimize this parasitic load effect (see there is a scientific reason for street dragging in the new car!)
  
• Traction battery limited braking - Whenever we can, we avoid braking or minimize how hard. It doesn't take much to exceed the MG2-to-traction battery power limitations, 36 hp (27 kW) which then requires Prius friction braking. In contrast, the new car has 168 hp (125 kW) of regenerative braking.

The 2010 Prius and our new car are different architectures and efficient driving requires a different style. If we apply new car style driving to the Prius it doesn't do so well. However, application of Prius habits to the new car plays very well.

Bob Wilson

 

Have you tried it with your PiP?

When I benchmarked pulse-and-glide in our 2003 Prius, I could get 10-15% more miles per gallon swinging between 25 to 42 mph. My acceleration was at cruise control rate and the glide was with engine-off in "N". But this best case is wildly impractical in ordinary driving. On top of that, our new car is nearly 2-3x more efficient than our 2003 Prius. You can reach a point where you're 'polishing the musket balls.'

The irony is the range limitations of our new car would beg doing everything possible to extend it YET I've never seen in the forums any mention of 'pulse and glide.' In fact, other than my graphs and benchmarks, they are pretty much 'not very technical.' Of course it could just be me. <grins>

So I am content to use automatic cruise control to pace myself behind my favorite Prius camouflage, large trucks or pickups towing trailers. Given how impractical pulse-and-glide is in ordinary traffic, I'm not sure there is anything to be gained.

Bob Wilson

 

I haven't tried rolling "N" in the new car, yet. I would have to set the cruise control to 'fixed' speed and then shift into "N" until it reaches 25 mph. Then hit resume and hope the new car would resume the fixed speed. Then repeat the runs at the fixed, equivalent speeds. If I think about it, I might get curious enough to try. Regardless, it is something best played when there is no other traffic around.

Bob Wilson