From the outside AP4 and Rally2 cars look very similar. But open up the bonnet and look under the bodyshell and they’re very different cars indeed.
Rally2 cars have proven popular throughout Europe and beyond, but in New Zealand, there’s a real love for AP4 machines.
One driver who has experience driving both cars is Hayden Paddon, and he’s taken the time to explain to DirtFish the differences between the two cars.
Engine
Let’s begin with the car’s main part – the engine. The AP4’s engine is less developed than the powerplant sat within a Rally2 car, but that doesn’t mean it’s any less competitive, as Paddon explains:
“The engine package we have here is very basic,” explains the Hyundai driver. “You’re talking steel block, Garrett turbos. It’s all designed to be more cost-effective.
“What that means is we’ve got an engine package and turbo package that’s probably in the vicinity of 10,000 euros. So, you’re talking a third to the quarter of a price to the R5 motor.”
The price tag attached to the engine would be appealing for any driver or team operating on a budget, especially when you discover that the AP4 engine produces more power than a Rally2 car. But it’s not all entirely rosy with the AP4 engine naturally having some drawbacks.
“The biggest plus for New Zealand Rally is all about being cost-effective,” said Paddon.
“We find that Rally2 cars in this part of the world when we’re a long way from the parts and from the support is sometimes harder to manage, so having a simple drop-in motor like this makes it a little bit simpler for smaller teams to be able to manage. But it does a job.
“As I say, we are probably talking anywhere from 10-30 horsepower more.
“[But it’s] down on torque and down on driveability. That means I put the AP4 in the bracket of being a slightly faster car when you get to fast stages, but a slightly slower car when you get to the twistier, more tepid stages.
Suspension
As you’d expect, when you’re building a product that is designed to be cost-effective, compromises need to be made.
As a result, it means the AP4’s suspension isn’t as well developed as the Rally2 equivalent, but it is more durable, meaning they shouldn’t need replacing as often over the course of a season, assuming the car isn’t involved in a crash.
“Suspension and chassis wise, the AP4 was designed with simplicity in mind, again for private teams to be able to run the cars and trying to keep costs down. So we have interchangeable uprights and suspension arms in all the corners,” said Paddon.
“Everything is built very heavy, which from a performance side is maybe not so perfect.
“The Rally2 parts are a little bit more lightweight, a little bit more developed but in this, we’ve got over-engineered wheel bearings, over-engineered uprights, over-engineered suspension arms. And what that means is it’s strong, it helps reduce the running costs for teams.
“In terms of the suspension, obviously very upright so we probably have limited travel compared to some Rally2 cars, but in terms of specification of the dampers, very much the same.
“Same technology inside these dampers as what you’ll find in Rally2 cars. Brake packages [are] all very standard. All the same across all four corners as a Rally2 car. So in general, it’s a good solid package in how it handles.
“It’s good for smooth types of roads that we have here in New Zealand. If we were to take this package into some of the rough rallies it may struggle compared to the Rally2 car, but for the purpose here in New Zealand, it’s absolutely perfect.”
Gearbox
The biggest difference between the gearboxes of the AP4 and Rally2 is the fact that the Ap4 has an extra gear.
But, just like the suspension, the AP4’s six-speed box is over-engineered so that it can cope with the demands of New Zealand’s rally stages without having to be rebuilt after each event, and it also has a few additional benefits.
“It’s all out of a rallycross car, so it has quite a heavy gearbox and differential,” explained Paddon. “As much as up to 10 kilos more than a Rally2 car.
“The big advantage for us when using this car as a rally and a hillclimb car, its driveline system is rated to 600 horsepower.
“So now, when we’ve got the horsepower, 2.4-liter motor in the car, we can run the same drivetrain and from an ingenuity side and flexibility side of the car, that’s awesome. We wouldn’t be able to do that with a Rally2 car.”
The main reason this was brought in for New Zealand rules was simply for a 'cool' factor. We wanted the cars to look cool out on the stages.Hayden Paddon on why AP4 has its trademark jumbo rear wing
Wings
One striking element of Paddon’s Hyundai i20 AP4 car is the rear wing. It’s bold, it’s brash and it adds another dimension to the car. And that’s exactly the point.
Yes, teams will be trying to get some aerodynamic benefit from the wing, but that wasn’t really why it was introduced to the regulations. It was all about creating a car that would get fans excited.
“The main reason this was brought in for New Zealand rules was simply for a ‘cool’ factor. We wanted the cars to look cool out on the stages.
“It gives some appeal for the spectators and just having a big wing on the back of this cars has made them look a bit angrier and engaged with the fans a little bit more.
“It does mean they have a slight aero advantage on faster rallies, but in saying that, the gap and the margin is actually quite small because a lot of the wings here in New Zealand are not done in wind tunnels.
“They are not finetuned for the shape or models of the cars. They are put on, as I say, simply for aesthetics. That’s probably the main aero difference between a Rally2 and AP4.”
It’s clear the two cars are built with very diverse philosophies in mind, but the results aren’t all that different.
“It’s very close, a lot closer than what some people think,” said Paddon when assessing how the two cars compare. “But I think they’ve been designed for different reasons.
“The Rally2 car is a well-developed car by the factories in Europe. They are the type of car people can get in and just drive and probably they are a lot easier to drive.
“A Rally2 car you can drive from 50%-100%. An AP4 car takes a lot more development. They are cheaper to run but it takes a lot more setup and to make these cars work you’ve actually got to drive them hard.
“If you drive this anywhere from 90%-100% they will work. If you drive it, 60, 70, 80% you find the car and chassis doesn’t actually work quite as well.
“In terms of pure performance, I’m just as happy driving the Rally2 car and believe we can achieve the same stage times or very close on the same rally. So yeah, gives a bit of variety to this end of the world.
“The main pros to these [AP4 cars] and why we see a lot of these in New Zealand is simply because the running costs of an AP4 is a lot lower and that’s what appeals to a lot of teams in this part of the world.”
The AP4 might be over-engineered, heavier and seems slightly basic compared to its counterpart, but on high-speed smooth gravel stages, it can still outrun a Rally2 car. And while a Rally2 might be better on slower stages it also costs a lot more to build.
The biggest difference between the two is driveability, but whichever way you look at it, both cars definitely have their place.
