An 18 MPG combined fuel economy isn’t going to win any awards, a figure that potential owners of the 2015 Audi RS 5 Cabriolet 4.2L 8-cyl understand and accept. This isn’t a car purchased for saving gas; it’s a performance machine designed to deliver exhilarating open-air driving thrills, and its fuel consumption is a secondary consideration for the target buyer: affluent enthusiasts who prioritize a visceral driving experience and distinctive styling over maximizing miles per gallon.

City and highway performance

The EPA estimates the RS 5 Cabriolet will achieve 16 MPG in the city and 22 MPG on the highway. These numbers accurately reflect the engine’s characteristics and the car’s weight. Stop-and-go traffic demands more fuel from the naturally aspirated 4.2L V8, while highway cruising allows the engine to operate more efficiently, though even then, its performance-oriented design means it’s never going to approach hybrid levels of frugality. The seven-speed S tronic dual-clutch transmission, while exceptionally quick and responsive, isn’t geared for maximum fuel conservation; its primary focus is on delivering rapid acceleration and holding the engine in its sweet spot for optimal power delivery.

Annual fuel cost

The EPA estimates the annual fuel cost for the 2015 Audi RS 5 Cabriolet at $3,200. This figure is calculated based on driving 15,000 miles per year, with a 55% city and 45% highway driving split, using national average fuel prices. It’s a useful benchmark for comparing the running costs of different vehicles, but remember that your actual fuel expenses may vary significantly depending on your driving habits, local fuel prices, and the type of fuel you use, this car demands premium gasoline.

Real-world expectations

While the EPA provides standardized fuel economy estimates, real-world MPG often differs. Aggressive driving, frequent use of the car’s launch control, and extended idling can all negatively impact fuel consumption. Careful driving, sticking to highway speed limits, and avoiding unnecessary acceleration can help you approach the EPA’s estimates. Owners of performance vehicles like the RS 5 Cabriolet often prioritize driving enjoyment over fuel efficiency, so it’s likely that many will experience MPG figures slightly below the official ratings. See RS MPG across all years.

How it compares

Compared to its competitors, the 2015 Audi RS 5 Cabriolet’s fuel economy is typical for its class. The BMW M4 Convertible, for example, achieves around 19 MPG combined with its turbocharged inline-6 engine. The Mercedes-AMG C63 S Cabriolet, with its powerful V8, delivers similar, if not slightly lower, fuel economy. The Lexus RC F, another performance coupe, hovers around the same 16-24 MPG range as well. While other convertibles like a base Porsche 718 Boxster are available with better MPG, their target markets and performance goals are different. The target buyer for the RS 5 wants the specific Audi RS experience, regardless of small MPG differences compared to other vehicles in its class. Consider all Audi fuel economy data relative to similar brands.

Tips to maximize efficiency

While squeezing every last mile from a gallon might not be the primary concern for an RS 5 owner, some techniques can improve fuel economy without sacrificing too much driving enjoyment. Avoid aggressive acceleration and hard braking. Smooth, progressive inputs will help the engine operate more efficiently and reduce unnecessary fuel consumption. This car loves to rev, but it doesn’t always need race-track levels of throttle.

Use the car’s Drive Select system to your advantage. The “Efficiency” mode can optimize the engine and transmission settings for improved fuel economy. Using this mode won’t transform the RS 5 into a hybrid, it can make a noticeable difference during relaxed cruising. “Dynamic” mode will encourage more aggressive transmission mappings that will rapidly deplete your fuel tank.

Ensure your tires are properly inflated. Underinflated tires increase rolling resistance, which reduces fuel economy. Check your tire pressure regularly and maintain the recommended levels, which can typically be found on a sticker inside the driver’s side doorjamb. Also, keep wheels properly aligned.

Minimize idling. If you’re stopped for more than a minute or two, turn off the engine. Idling consumes fuel without moving the car. Modern vehicles like the RS 5 are designed to restart quickly and efficiently.

Reduce weight. Remove any unnecessary items from the car. Extra weight puts additional strain on the engine, which reduces fuel economy. While cleaning out the glovebox won’t suddenly add 5 MPG, it’s one small factor that can contribute to overall efficiency.