Green machines on display at Denver Auto Show

The Denver Auto Show boasts more than 20 alternative-fuel vehicles including the only commercial hydrogen-powered vehicle in the state.

"We have all types of green machines here," show producer Barbara Pudney says. "You're going to get that feel of anything and everything that is green, and where auto manufacturers are going with their green machines."

Electric, hybrid, natural gas and clean diesel vehicles are all part of the third-largest auto show in the country, which continues through Sunday at the convention center in downtown Denver. 

The Mercedes-Benz F-Cell is the only hydrogen vehicle in Colorado outside of the National Renewable Energy Laboratory in Golden. For now, the lab is the only place to refuel the F-Cell in Colorado. But as more fueling stations are built, manufacturers are expected to offer more hydrogen vehicles. The F-Cell could be available more widely next year.

The vehicle's only emission is water vapor. "What could be better than that?" Pudney says.

Here are a few other things to note at the show:

• Fuel economy gains: Manufacturers are continuing to boost fuel efficiency as they work to meet increased federal standards. By 2016, new cars will need to average 36 miles per gallon. For example, the 2015 Ford F-150 pickup truck is lighter than its predecessor making it more efficient but Ford says it's more dent-resistant and safer than ever.
• New technology: Vehicles now offer a range of technologies to make driving easier and safer. They include blind spot indicators, collision-avoidance systems, rear-view cameras and adaptive cruise control that helps slow your vehicle if the car ahead of you loses speed. General Motors is touting remote access to its vehicles through its On Star System. Owners can use a iPad or iPhone to check tire pressure or fuel levels as well as to start a vehicle remotely in the winter.
• Specialty vehicles: The show includes some concept cars that may give a glimpse of the future. One of the most popular tricked out vehicles is Hyundai's Walking Dead Zombie Machine, perfect for fans of the television show. The car boasts a plow, armor, wheel spikes, escape hatch, food storage, weapons and a first aid kit. But it's just for show. It's not street legal.