Auto-Stop Engine

Yesterday I had to take my car in to the dealership for its 25,000 mile service (and I've only had the car 17 months). They gave me a loaner car. It was a not-quite-as-nice but newer (2015 model) version of my car. And it was black, not white. I did learn that black is harder to spot in a Costco parking lot.

But one feature it had I'd never experienced before: engine auto stop. That is, when the car was stopped (at a stop light, for instance), the engine would shut off. When you took your foot off the brake, the engine would start.

This is one way automakers are attempting to improve gas mileage to meet the new (and frankly ridiculous) Corporate Average Fuel Economy (and don't get me started on those) requirements.

This was a change I could live with, sorta. When you stopped at a stop light or stop sign, or anywhere more than just a few seconds, the engine would shut down. This was a slight shudder in the car when this happened. The air conditioning would also not blow nearly as hard and I thought it must be running off the battery. The tachometer would drop to zero (labeled "Ready"). When you lifted your foot from the brake, the car would instantly fire up (with a slight shudder) and pull away. Except for the AC and the shudder when it stopped and started, it was seamless. There was also a small green indicator on the dashboard display when engine was stopped.

When you stopped the engine, the tachometer needle dropped to a lower position labeled "Off."

An interesting thing, however, was that after the car had sat in the hot sun while we had lunch, the auto-stop stopped working and a the green indicator was white with a line through it when the car was stopped. I decided this was because the car had decided to keep running so the AC could keep going full blast to cool the car's interior.

The biggest problem I see with this is constantly starting and stopping the engine (and can you imagine this in stop-and-go traffic) would probably wear the starter and the engine more than keeping it running. But the CAFE standards say nothing about parts longevity, just better gas mileage.