How does one know if a rental car takes diesel or gasoline?
Quite unlikely, but what if I rent a car and forget to ask if it takes diesel or gasoline? Is it customary that it's written next to the gas tank inlet (I've only rented a car once, and this was the case).
Or is this something that is easily deduced from the car name? Any other method?
Small hose nozzle opening PROBABLY - as per Affeter. BUT don't do it. Just don't. You will almost certainly not be provided with a diesel car unless you ask for one. Regardless - if you put petrol in a diesel car you risk major damage. Odds are you will be liable due to the agreement that you have signed. (We travelled for 4 weeks in Europe in Eurolease turbo-diesel manual Peugeot 307 - a pleasantly surprisingly good performing car).
@RussellMcMahon I did get diesel cars without specifically asking for one (most recently in Ireland IIRC).
@RussellMcMahon: true you have to pay extra for diesel, but it's not unusual to get free upgrade without asking, just because they don't have the cheaper car you've reserved.
I once found myself in that situation after reaching the petrol station. So I searched for the manual of the car and found it. It gave the following helpful information: "If your car has a diesel engine, put diesel into the tank. If your car has a petrol engine, put petrol in the tank. ". I kid you not.
It's common in Europe for many cars to have a Diesel or Gasoline version.
Usually, but it is not a rule, if the model of the car has a letter D it's a Diesel car, but this is not a rule. It's not a rule as well for the car to have a letter on the model name.
Usually in Diesel cars you will find some warnings about it.
- The rental car agent will tell you
- Next to the gas tank a warning about the type of petrol.
- The diameter of gasoline hose has a different size of a diesel hose. It will be hard to put the wrong hose inside the tank.
- The label on the key could have DIESEL written on it (HERTZ does that)
I know. I only wanted to point out that the advice given above can be misleading: **'if the model of the car has a letter D it's a Diesel car'**
@SantaC.: I'd understand that as `D` alone, not in combination with other letters. Which was in fact true. 30 years ago ;-)
@Karlson: most Mercedes-Benz diesel cars have `CDI` in the version name, with notable exception of ones equipped with `BlueTec` (which is diesel-only technology).
This is incredibly misleading. You hinted at the best answer. Inside the fuel filler flap it will read "unleaded gasoline only" or "diesel only". Usually with a minimum octane rating for gas and maybe a centane rating for diesel.