Quick Summary:
- Choose Regular 87 (E10) unless the fuel door states otherwise.
- Avoid E15/Unleaded 88 unless the vehicle explicitly permits E15.
- Keep the fuel receipt and grade proof in case of disputes.
- If you misfuel, stop driving, call roadside help, document everything.
Seeing “Unleaded 88” or “E15” at a Florida petrol station can be confusing when you are on a car hire agreement and just want to refuel correctly. In the UK, you rarely have to think about ethanol percentage at the pump. In Florida, ethanol blends are common, labels vary by brand, and the wrong choice can lead to performance issues for some vehicles and a potential bill if the hire company treats it as misfuelling.
This guide explains what E15 (often marketed as Unleaded 88) is, how to choose the right pump label for most hire cars in Florida, why some fleets treat E15 as risky, and what to do if you accidentally fill the wrong grade.
What is E15, and why is it labelled “Unleaded 88”?
E15 petrol contains up to 15% ethanol, compared with the more common E10 that contains up to 10% ethanol. In the US, many stations sell E10 as “Regular Unleaded” and label it as 87 octane (AKI), which is the standard rating used on American pumps. E15 is sometimes sold as “Unleaded 88” because the octane rating is typically 88 AKI.
That “88” can look like a premium upgrade if you are thinking in simple octane terms, but ethanol content matters just as much as octane. Ethanol changes how fuel behaves, including how it absorbs water and how it interacts with seals, hoses, and fuel system components in vehicles that were not designed or certified for higher ethanol blends.
Which pump label should you choose for Florida car hire?
For most car hire vehicles in Florida, the safest default is to choose “Regular Unleaded 87” that is typically E10. It is the closest match to what the majority of US petrol engines are designed to use day to day, and it is the grade most hire fleets expect customers to buy unless the vehicle states otherwise.
Here is the practical decision process that avoids mistakes:
Step 1, check the fuel door and the handbook. Open the fuel door and look for a sticker that says “Unleaded gasoline only” and sometimes includes “E10” or “up to 10% ethanol”. Some vehicles will explicitly state “E15” is acceptable, but many do not. If the label specifies a minimum octane, follow that instruction.
Step 2, match the pump label to the vehicle requirement. If the car asks for 87 AKI, buy 87. If it asks for 91 or 93, buy that. Do not substitute E15 just because it looks like a middle option.
Step 3, avoid confusion at the nozzle. At some Florida stations, E15 is placed between 87 and 93 and looks like a standard petrol choice. Look for “E15”, “15% ethanol”, or “Unleaded 88” on the button, the pump topper, or the price display.
If you are collecting a vehicle around Miami, Fort Lauderdale, Tampa, or Orlando, the same rules apply. If you are comparing pick-up points or vehicle types through Hola Car Rentals, these location pages may help you plan logistics and fuel stops near major routes: car rental at Tampa Airport, car hire in Fort Lauderdale, Enterprise in downtown Miami, and Hertz near Disney Orlando.
Why E15 can be risky for some hire fleets
Even though many newer vehicles can run on E15, hire companies often manage a mixed fleet with different model years, engine types, and usage patterns. That makes E15 a risk management issue. The concerns typically fall into four categories:
1) Vehicle compatibility is not universal. In the US, E15 is generally approved for light-duty petrol vehicles from model year 2001 onward, but there are exceptions, and not every manufacturer recommends it. Some engines are calibrated for E10 and may not perform as intended on E15. A fleet operator cannot easily verify what was pumped into the tank after the fact.
2) Water absorption and storage effects. Ethanol is hygroscopic, it attracts water. In humid Florida conditions, and especially when a vehicle sits between rentals, higher ethanol blends can increase the chance of phase separation if water contamination occurs. This is a bigger concern for vehicles not turned over frequently or those stored with partially filled tanks.
3) Fuel system materials and wear. Higher ethanol content can be harder on certain rubber components and seals in older designs. Many hire fleets keep cars relatively new, but “relatively” can still mean vehicles that are not ideal candidates for E15.
4) Misfuelling policies can be strict. Some car hire terms treat any fuel not meeting the manufacturer requirement as misfuelling. If a vehicle later shows a fuel system fault, the hire company may investigate refuelling receipts, onboard diagnostics, or contamination tests, and attempt to recover cleaning, towing, or repair costs.
None of this means E15 will automatically damage a modern hire car. It means the downside risk is not worth it when E10 87 is widely available and usually cheaper than premium grades.
Will using E15 automatically cause damage fees?
Damage fees are not automatic, but they can happen if E15 is considered an incorrect fuel for the specific vehicle, or if there is a related issue and the provider attributes it to misfuelling. The practical problem is proof. If the vehicle is not labelled as E15 compatible and you used it, it can be difficult to argue later that it was fine, especially if you did not keep a receipt showing exactly what you purchased.
To reduce the risk of being charged unfairly:
Keep the fuel receipt and make sure it shows the grade (87, 89, 93, or “Unleaded 88/E15”) and the time and location.
Take a quick photo of the pump selection before you squeeze the handle. A photo of the vehicle fuel door label can also help if there is a dispute about what was required.
Refuel close to drop-off so your receipt clearly relates to the return condition. This is useful even when you are sure you chose the correct grade.
How to spot E15 at Florida petrol stations
Florida forecourts can be busy, and labels are not always consistent. Watch for these common signs:
“Unleaded 88” often equals E15. The number refers to octane, not ethanol percentage.
“E15” may be printed near the button or on a yellow label. Some pumps add wording like “up to 15% ethanol”.
Green or blue branding is sometimes used for ethanol blends, but colours differ by chain, so rely on the text.
Separate nozzle position can trick you. E15 is frequently positioned as a “value” option between 87 and premium. Do not pick it just because it looks like the middle grade.
What if your hire car says premium fuel is required?
Some Florida car hire vehicles, particularly certain turbocharged models or luxury trims, may require premium (often 91 or 93 AKI). If the fuel door says “premium required”, use premium. If it says “premium recommended”, you can usually use regular, but you may notice reduced performance or fuel economy.
Premium is not the same thing as E15. You can have premium E10, and you can have E15 that is not premium in terms of ethanol content. Follow the minimum octane stated by the manufacturer first, then avoid higher ethanol blends unless the vehicle explicitly allows them.
What to do if you accidentally fill E15 or the wrong grade
Mistakes happen, especially when you are juggling an unfamiliar car hire vehicle, a US pump, and traffic around tourist routes. What you should do depends on what went wrong and how much fuel was added.
If you selected E15 but the vehicle likely needs E10 only: If you have not started the engine yet, do not. Keep the receipt, take a photo of the pump grade, and call the roadside assistance number from your rental documents. They may advise draining the tank or diluting with the correct fuel depending on the vehicle and the amount added.
If you added a small amount of E15 into a mostly full tank of E10: In many cases, the effective ethanol percentage will be closer to E10 to E12, but you should still report it and follow the provider’s guidance. Do not guess, because policies differ.
If you put the wrong octane in: If the car requires premium and you added 87, it is usually less immediately risky than misfuelling with diesel, but it can cause knocking or reduced performance. Call for advice, and avoid hard acceleration until resolved. Some providers will tell you to top up with premium at the next stop to raise the overall octane.
Document everything: Keep receipts, note mileage, and write down what happened while it is fresh. If a fee is later questioned, clear documentation helps.
Extra Florida car hire fuel tips that prevent headaches
Do not rely on the word “regular” alone. Some stations show “Regular” next to Unleaded 88 or have promotional signage. Always look for the ethanol label and the octane number.
Avoid “Flex Fuel” assumptions. Some vehicles are flex-fuel (able to use E85), but do not assume your hire car is one. E85 is a completely different product and is clearly labelled, but confusion can happen.
Pay attention to the fuel type at pick-up. At handover, quickly check what the fuel door says. It takes 10 seconds and can save a dispute later.
Consider your vehicle type. People carriers can be more sensitive to load and driving style, so sticking to the recommended fuel matters for drivability. If you are travelling with family and luggage, you might be comparing larger options such as a minivan rental in Tampa. Regardless of vehicle size, the fuel door label is the rulebook.
FAQ
Can I use Unleaded 88 (E15) in a Florida car hire vehicle? Sometimes, but only if the vehicle explicitly allows E15. If the fuel door or handbook only mentions E10 or does not mention E15, choose Regular 87 (typically E10) to avoid compatibility and policy issues.
Is Unleaded 88 better than Regular 87? Not necessarily. Unleaded 88 often has a slightly higher octane number, but it also has higher ethanol content. For many hire cars, Regular 87 E10 is the safest, most expected choice unless premium is required.
How do I prove what fuel I put in if there is a dispute? Keep the receipt showing the grade and take a photo of the pump selection. If possible, also photograph the fuel door label that states the required octane or ethanol limit.
What should I do immediately after filling the wrong grade? If you can, do not start the engine. Call the roadside assistance number in your rental documents, explain the fuel grade and quantity, and follow their instructions. Keep all receipts and notes.
Will misfuelling always lead to damage charges? Not always, but it can if the fuel used is outside the vehicle requirements or if a related fault occurs. Choosing the recommended grade, keeping receipts, and reporting mistakes promptly reduces the risk.
