Super-efficient light-truck engines are coming, but don't expect to notice.
That's the impression we came away with after driving General Motors' latest light truck concepts. The reason: something engineers call transparency, an effort to make new technology do its thing without anyone noticing.
In a prototype Sierra pickup, we tested a V8 engine that keeps half of its cylinders closed until more power is needed. The key: a tricky lifter that closes valves when prompted by an engine computer. At that point, the air trapped inside the cylinders acts like a spring, neither absorbing nor creating energy. The fuel economy gains come from running the remaining cylinders
at improved efficiency levels.
A light on the instrument panel is the only hint that any of this is happening. During our tests on the highway and in stop-and-go traffic, the engine ran on four cylinders a full 40 percent of the time. GM plans to introduce the system this fall as an option in
certain heavy-duty trucks, hoping for mileage gains in the 8 percent range.
We also tested a so-called mild hybrid in a prototype Denali sport-utility. With this setup, an innovative starter-alternator cuts the engine at a stop and stores energy from braking in a secondary battery system. During our short drive, the engine action was barely noticeable. The best part: At one point, we stopped to make popcorn, plugging a microwave into the alternator's auxiliary power output.
Mild hybrids offer fuel economy gains of around 15 percent, and should hit the market in some SUVs by 2003.
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.