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资讯 燃油经济性，无疑是过去几十年来汽车技术发展的核心驱动力之一。随着企业平均燃油经济性（CAFE）标准不断提高，各大汽车制造商也在想方设法从各个环节提升车辆能效。
发动机自然是关键之一。许多厂商都已广泛应用汽油直喷（GDI）技术，使其成为当前美国最常见的发动机类型。然而，随着GDI发动机的普及，北美各地燃油中添加剂的配方却未能同步升级，这反而可能限制发动机发挥其全部的节能潜力。
为此，“顶级汽油”计划即将推出升级版。这是一则自愿性标准，目前大多数主流燃油供应商都已加入。本文将带您了解：GDI发动机为何需要更清洁的喷油器、清洁如何影响实际油耗和排放，以及这次标准更新对行业和车主为何是个好消息。
汽油直喷 vs. 进气道喷射
要理解高品质燃油为何对如今的发动机如此重要，我们得先弄清楚GDI发动机和过去的技术有何不同。
GDI和进气道喷射（PFI）发动机最主要的区别，在于喷油器的位置。在PFI结构中，喷油器安装在燃烧室之外，燃油先喷入进气歧管，再随气流通过进气门进入燃烧室。正因为燃油会流经气门，它自然就能带走一部分沉积物，形成一种自我清洁的效果。
而在GDI结构中，喷油器直接安装在燃烧室内部。这样做的好处是发动机控制单元（ECU）可以更精准地控制喷油，因此效率比传统PFI更高，油耗更低、动力更强、排放更干净，这也是厂家纷纷转向GDI的原因。
不过，将燃油直接喷入燃烧室也带来了一些意想不到的问题。燃烧室是发动机中温度最高、工况最恶劣的区域，高温高压容易导致喷油器和活塞顶部在车辆行驶里程并不高时就积碳。（相比之下，PFI发动机即使里程很高，积碳通常也没这么严重。）由于GDI发动机每次喷油量都需要极其精确，积碳一旦形成就会干扰这一过程，进而影响发动机效率、动力和排放表现。
这些问题不会立刻出现。但大约行驶2万英里后，其实这对于一辆家用车来说并不算久，而此时GDI发动机的油耗就可能因积碳增加而明显上升。
好燃油有多重要？
好消息是，采用先进添加剂配方的高品质汽油，确实能预防甚至清除GDI发动机喷油器上的积碳。虽然这类燃油市场上已经能买到，但它们的普及速度远远赶不上GDI发动机的装车速度。这一局面，有望在未来两年内改变。
目前，美国汽油唯一必须遵守的强制性标准，还是1995年《清洁空气法案》所制定的。该法案通过淘汰含铅汽油、规范添加剂、推广新配方汽油和超低硫汽油，有效控制了尾气污染。
但三十年过去，这份标准已无法满足GDI发动机的实际需求。而2005年推出的“顶级汽油”计划，虽然成功推动了市场燃油品质的提升，比如约八成的加油站都在使用这种“高货”，但其标准同样是二十年前制定的，未能充分考虑最新GDI发动机的性能要求。
于是，“顶级汽油+”标准应运而生，将于2027年2月正式实施。届时，参与该计划的燃油企业都必须对配方进行相应升级。
添加剂如何提升燃油效率？
新的“顶级汽油+”标准将基于一系列针对GDI发动机的测试结果。这些测试不仅评估燃油保持喷油器清洁的能力，还包括颗粒物排放、早燃表现等关键指标。特别值得一提的是，新标准强调燃油必须能“清除”而不仅是“防止”积碳，也就是说，即使用户的喷油器已经脏了，新燃油也应当能帮助清洗干净。
这对广大车主来说是个实实在在的好消息：毕竟GDI发动机从2010年就开始普及，却一直缺少针对性的燃油解决方案。新配方有望帮助这些“老车”恢复部分油耗表现和排放水平。
添加剂的工作原理并不复杂：先进的积碳控制添加剂会主动吸附在喷油器表面的碳沉积物上，将其带入燃油中一并燃烧，最终通过催化转化器处理掉。久而久之，使用高品质燃油的GDI引擎就能逐渐恢复状态，运行起来更接近最初设计的理想状态。
Gasoline direct injection (GDI) engines are the most common technology on American roadways in 2025, and soon, an industrywide gasoline quality standard will better reflect their unique operational needs. Here’s why that’s important.
It’s no secret that fuel economy has been one of the greatest driving forces of automotive evolution over the past several decades. As corporate average fuel economy (CAFE) standards have grown increasingly lofty, OEMs eke out new efficiencies from every area of the vehicle.
One of those areas, of course, is the engine, and many OEMs have deployed gasoline direct injection (GDI) technology, which is becoming the most common engine technology on American roadways. But while GDI engines proliferate, varying fuel additization throughout North America has not necessarily kept pace with their unique needs and can, in fact, hinder those engines from meeting and sustaining their full fuel economy potential.
A coming upgrade to the Top Tier fuels program – a voluntary standard in which the majority of leading fuel marketers participate – seeks to change that. This article will explore the unique needs of GDI engines with respect to the fuels ’ability to contribute to greater fuel injector cleanliness, how that cleanliness impacts real-world fuel economy and emissions, and why the coming update is a positive step for the industry and consumers.
Gasoline direct injection vs. port fuel injection
To understand the impact that higher-performing fuels can have on today’s most common engine technology, it’s useful to understand how GDI engines differ from those of the past.
The primary difference between GDI and port fuel injection (PFI) engines is the location of the fuel injector. Within PFI architectures, the fuel injector is located outside of the combustion chamber; fuel is injected into the intake, which is then delivered over the intake valves into the combustion chamber as required by the current duty cycle. Here, because of how the fuel enters the intake, it naturally flushes over these valves, creating a type of natural cleaning cycle simply because the process prevents the majority of buildup from forming.
In comparison, GDI architectures place the fuel injector directly in the combustion chamber, where it can be more precisely controlled by the vehicle’s engine control unit (ECU) and is thus more efficient than a traditional PFI setup. There are major advantages to this architecture, including improved fuel economy, increased power & torque, and reduced emissions – and it’s why OEMs have made the shift.
Engines designed to inject fuel directly into the combustion chamber come with some unintended side effects. The combustion chamber is the hottest and most intense area of operation, where elevated pressure and temperatures can cause carbon to build up prematurely on the injector and piston tops at lower overall vehicle mileage (comparatively, this kind of buildup typically never gets this bad even when a PFI vehicle hits high mileage). Because precise amounts of fuel are sprayed during each injection event, premature carbon deposits can interrupt that precision, and have damaging impacts on the engine’s efficiency, power, and emissions.
These impacts aren’t noticeable in real time. However, within just 20,000 miles – not long into the course of a typical passenger car’s anticipated service life – GDI engines can lose significant fuel efficiency as deposits continue to build up.
The importance of high-quality fuels
The good news is that high-quality gasoline formulated with advanced additive chemistry can help prevent and even clean up deposit buildup on fuel injectors in GDI engines. And while such fuels can be purchased today, their widespread availability has not matched the pace at which GDI engines have become the dominant engine technology in the American car parc. But that may change within the next two years.
Today, the only mandatory standards that must be met by gasoline sold in the United States are those established by the 1995 Clean Air Act (CAA). The CAA set minimum gasoline requirements to reduce air pollution by phasing out leaded gasoline, regulating fuel additives, and establishing standards for reformulated gasoline (RFG) and ultra-low sulfur gasoline (ULSG) to control smog-forming pollutants and tailpipe emissions from vehicles.
But because the CAA was passed 30 years ago, it does not account for the operational conditions of GDI engines. Elsewhere, the Top Tier Gas program was established in 2005 to help elevate gasoline quality throughout the marketplace. While this program is not mandatory, roughly 80% of major fuel marketers participate. For program participants, every pump at every station must dispense fuel that meets program standards, making it easy for everyday drivers to find higher-quality fuel.
However, Top Tier standards were established 20 years ago and, again, do not fully account for the performance requirements of the latest GDI engine architectures. To that end, Top Tier introduced an upgrade to the standard, called Top Tier+, that will take effect in February of 2027. Fuel marketers have until then to make the necessary additive changes to their fuel formulations to continue participating in the program.
How additive science contributes to optimal fuel efficiency
New Top Tier+ standards are based on fuel performance in a series of new tests specific to the GDI market. They will evaluate the fuel’s ability to contribute to greater injector cleanliness as well as other critical performance criteria, including particulate matter generation and pre-ignition performance. Importantly, Top Tier+ will require cleanup performance with regard to fuel injector deposits rather than keep-clean performance. This means Top Tier+ fuels must be able to help eliminate deposits from already-dirty fuel injectors. Broadly, this should benefit the entire modern car parc – GDI engines have been in the field since 2010 without a dedicated fueling solution, and new formulations should be able to help restore some fuel economy and emissions benefits to these vehicles.
Fuels can achieve elevated levels of performance in these areas via the incorporation of new additive chemistries. For example, at a basic level, advanced deposit control additives work by attaching themselves to carbon deposit molecules that have dirtied the fuel injector. The additive pulls those molecules into the fuel stream, where they combust along with the fuel and are then mitigated by the vehicle’s catalytic converter. Over time, a GDI engine serviced with high-quality fuel will regain efficiency that had been hindered by excessive injector buildup, restoring the engine’s operation closer to its original design intent.
作者： Brett Blackburn
来源：https://www.sae.org/articles/2025/10/higher-quality-gasoline-keeps-modern-engines-clean-efficient
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