Autos

Audi A4 3.0 TDI

On sale: Early 2009

Fuel savings today, 15,000 miles: $987
Year-ago savings: $1,212
Difference: $225
Mileage: 34 mpg (combined, estimated)
Closest gas model: Audi A4 3.2
Mileage: 21 mpg (combined city/highway)

The Audi A4 3.0 TDI shares an engine with the Q7 3.0 TDI, but the smaller, lighter diesel A4 will get better gas mileage. Audi says it will average 34 mpg. That represents close to $1,000 a year in fuel-cost savings, vs. the gasoline-powered Audi A4 3.2, assuming 15,000 miles a year. However, if Audi charges more for the diesel model, like rival Mercedes-Benz does, it may take some time for the savings in fuel costs to make up the difference for the more costly diesel model.