Raising the fuel economy of cars and light trucks to 35 mpg won't be easy, but a batch of off-the-shelf technologies can bring automakers close to the goal.

The downside: Implementing them will be expensive for automakers and consumers. Here are the five top currently available technologies, along with the estimated per-vehicle cost to the automaker:

1. Diesel engines: Diesels can deliver fuel economy gains of 25 to 30 percent over similar sized gasoline engines. For example, a two-wheel-drive Chevrolet Silverado pickup with a 5.3-liter V-8 gasoline engine gets 22 mpg on the highway. With a 4.5-liter diesel, a six-speed automatic and a couple of other tweaks, this truck can achieve close to 30 mpg highway. Cost: $4,000 to $6,000.

2. Hybrids: The Toyota Prius already achieves more than 45 mpg. Adding a plug-in feature to full hybrids - a technology featured on the Chevy Volt - would allow a fuel economy rating as high as 150 mpg for short trips. Less costly "mild" hybrids such as the Saturn Vue Green Line can deliver a 20 percent improvement in fuel economy. Cost: $2,000-plus.

3. Turbochargers: Combined with gasoline direct injection, variable valve timing and other technologies, turbos allow automakers to use smaller engines without hurting performance. Audi, Ford, Mazda, BMW, Chrysler and GM are adding turbochargers to their lineups. Cost: $300 to $500.

4. Electronics: Replacing slow, heavy mechanical systems with light, faster-acting electronics improves fuel economy in several ways. An electric power steering system, for example, reduces drag on the engine and weighs less. LED lighting requires less electricity, which allows the use of lighter wiring harnesses. Cost: $100.

5. Lightweight materials: Aluminum, magnesium, carbon fiber and plastics cost more than steel, but save weight. Cost: Varies by vehicle and material.

You may e-mail Richard Truett at rtruett@crain.com