The Audi B5 S4 and RS4 are legendary vehicles. It’s an updated version of the original A4 that delivers a fantastic driving performance. Although the first models were released in Europe, Americans started driving them a couple of years later.
The B5 S4 and RS4 models sold in the United States had to meet emissions guidelines, which means the Euro-style is more powerful. Even with that change, drivers still get 250 HP and 258 pound-feet of torque from a V6 2.7L twin-turbo engine.
If you upgrade the exhaust system and a couple of chips, you can reach 350 HP with this setup. When you drive the RS4, you can get an even better result.
B5 S4/RS4
The Audi B5 S4 and RS4 are two vehicles built between 1999-2001. The latter version delivered more power and passenger space, while the former gives the driver more of a sports car appeal. Although these vehicles are about 20 years old, they still deliver an excellent driving experience.
The Audi B5 platform was the second generation of the S4 and RS4 after the C4 powertrain introduction in 1991.
It comes in two versions. You can get the saloon/sedan model, or an estate version called the Avant, which was a station wagon.
Production ceased in 2001 for the B5, although the vehicles continued to be available in the United States through the 2002 sales year.
What Are the Differences Between the B5 S4 vs. RS4
When looking at the differences between the B5 S4 and the RS4, you’ll find several minor changes that lead to improved performance with the upgraded option.
- It comes with an airbox that offers an additional vacuum-activated intake valve.
- It delivers bigger intercoolers and an 83 mm MAF.
- There is a larger throttle body, intake runners, and intake piping in multiple locations.
- You will see larger injectors, downpipes, and exhaust structures with a better fuel pump.
- It uses a 6-speed manual only, which means you get a stronger clutch.
- The design uses flared front and rear fenders, including new rear door panels.
- It incorporates a carbon-fiber trim with updated Recaro seats, unique sills, and improved bumpers on the front and rear.
Although the differences are essential to review, you’ll also want to take a closer look at the pros and cons of each vehicle.
The European model might be slightly different from the American version of the B5 S4 and RS4, but the various advantages and disadvantages are still the same. You’ll just want to increase the power and acceleration stats a little with the comparison.
Here’s a look at the pros and cons of driving the Audi S4 today.
| List of the Pros of the Audi S4 | List of the Cons of the Audi S4 |
| • The base cost of the 2020 Audi S4 is reasonable, starting at under $51,000 in most markets. • If you purchase the available upgrades, you can have the price reach close to $70,000. • Newer models can reach nearly 350 HP at 6,200 RPM with features added at the dealership. • Drivers receive an excellent ride quality in virtually any environment or situation, including in winter conditions. • The steering and handling make it a joy to get behind the wheel of this vehicle. | • The new models have a relatively high price for someone who wants a commuting vehicle. • The B5 S4 is the better choice for those needs. • Most models receive a mild refresh each year. • The current 2020 S4 feels a lot like the older RS4 options in the used market today. • You receive a non-linear brake feel when driving this model, which isn’t always an enjoyable experience. |
Since the B5 S4 is around 20 years old today, you’ll find that the used car prices make it incredibly attractive to try this vehicle. If it is used for driving, a blue-booked value hovers around $3,500.
When the B5 S4 comes with an aftermarket body kit, wheels, and an automatic transmission, it can still sell for more than $10,000.
If you purchase the B5 S4 instead of going after the new Audi S4 model, you’ll want to ensure the water pump and timing belt have received attention within the past couple of years.
With those points in mind, the B5 S4 is still an excellent option for personal transportation.
If it doesn’t feel quite suitable for your needs, the B5 RS4 is an excellent solution to consider as an alternative.
| List of the Pros of the Audi RS4 | List of the Cons of the Audi RS4 |
| • The RS4 delivers an improved traction profile for driving. • You can feel the low center of gravity helping to hug the curves and corners that you encounter on the street. • It’s easy to get behind the wheel and feel comfortable at fast speeds because of how smooth it drives and accelerates. • Although the cost is a little higher, you receive a high-performance outcome with the most sports-focused design you can find on the B-auto platform. • It uses a wider axle track than the RS4, accommodating the Avant version body type. | • You’ll end up paying more for the RS4 for what amounts to a few minor upgrades to the average driver. • It doesn’t make sense for vehicles used as a commuter. • The back end can feel a bit loose when handling curves and corners at higher speeds. • When the B5 was originally introduced, it was only produced as an estate car or station wagon. • You have to step up to the B7 if you want something that looks and feels more like a sports car. • Only 6,000 units of the B5 RS4 were produced between 1999 and 2001, making it challenging to find this model on the used market today. |
Although you can compare the performance specs for the B5 S4 vs. RS4 all day, the bottom line of these vehicles is that the first is a sports car, and the second is meant more for families. The engine might be sportier and high-performance, but you’re essentially driving a station wagon with this model.
The B5 also has the side guard curtain airbag system that Audi produced and uses HID (high-intensity discharge) Xenon headlamps.
Between 2001-2005, Audi didn’t produce an RS4 using the B6 platform. That’s why the model skips from the B5 to the B7.
How to Increase Your Horsepower on the B5 S4 or RS4
Modern vehicles have been fast off the showroom floor for a couple of decades now. One could even say that the B5 S4 and RS4 helped to start that trend with their affordable high-powered solutions.
That doesn’t mean you’ve reached the peak performance of your setup when driving away from the dealership. You can make a few minor tweaks or overhaul the entire system to get even more power from your Audi.
Here are some of the most popular ways drivers are working on getting more HP when they’re behind the wheel.
1. Upgrade the cold air intake.
Upgrading the intake on the Audi B5 S4 or RS4 is one of the easiest ways to start unlocking the extra horsepower you want from your ride.
The factory setup is fine for most driving circumstances, but there are some places where an aftermarket change is useful. If you drive in high-altitude locations frequently, you’ll notice improved performance with this change.
The best setups use a free-flowing air filter to produce more HP because they allow the engine to start breathing better. It also needs the correct heat shield to prevent sucking the hot air from the engine compartment because that action would negate the gains.
2. Add a performance exhaust.
Audis always benefit from a performance exhaust. It helps everything flow better than the stock setup from the factory. Although most upgrades in this category produce more noise, you can save a few pounds from the car’s weight profile with this investment.
You might need a downpipe or headers to maximize your gains, but it’s still worth the time and effort to look at these options.
3. Change the software and chips.
The most effective way to add power to your Audi is to modify the engine control unit (ECU). This part gets tuned to a conservative figure to let lower-grade fuels function while minimizing internal stress on the engine components.
If you install aftermarket software and swap out a few chips that keep your HP numbers down, you’ll get to take full advantage of what your engine can produce.
When you change the software and chips in your Audi S4 or RS4, you’ll need to use premium fuel to prevent future problems. If you keep running the cheap stuff, the power delivery won’t be where you want it to be in the future.
Only purchase Audi software changes from reputable tuners. Engines tend to be sensitive to change, which means you’ll need to think about making changes in stages for some vehicles instead of doing everything at once.
4. Use forced induction to get more power.
When an engine is naturally aspirated, using this technique to get more horsepower can deliver massive gains. You can achieve the result by getting a supercharger or turbocharger for your Audi B5 S4 or RS4.
A turbocharger generates power by taking the leftover exhaust gases to spin a turbine. This activity forces more air into the engine, allowing it to burn more fuel for added energy.
Superchargers force more air into the engine through belt-driven mechanisms. That means it needs some power to operate, but you’ll also get an instant response behind the wheel. Supporting modifications might be necessary with this aftermarket alteration for your Audi, making it one of the more expensive choices out there to get more HP.
It might cost about 10% of the original MSRP to achieve the results you want with this methodology.
5. Do an engine conversion.
When you don’t have more upgrades to consider with your Audi B5 S4 or RS4, this final option lets you grab some more horsepower. An engine swap can be a plug-and-play experience with the right items, but it might need some extensive fabrication to make everything fit.
Unless you’re a mechanic or a highly experienced DIY’er, this option is usually handled better by a professional.
A Final Thought: Audi B5 S4 vs. RS4
The Audi B5 S4 vs. RS4 debate settles more on transportation needs or the frame you want to create a new build more than anything. Although the models are aging well compared to most options from other automakers, you’ll find extra performance is available in the latest versions.
I’ve always appreciated how Audi creates an authentic vehicle. When you get behind the wheel, you know that it was built with love and care.
After making some minor modifications, you can get the S4 or RS4 to where you want it to be from a performance stance. If you’re starting from scratch, you can usually find one for less than $10k, swap out the old engine for a new one, and upgrade the other components without reaching the price of the latest version.