I’ve never bought premium fuel in my life, but I have filled my new defender 3 or 4 times now with the high octane fuel that they recommend. Is this really necessary or can you get by with regular 87 octane? I’m really getting tired of the 50 to 60 cent or more mark up for premium. For what it’s worth, I’m getting 20+ mpg on all highway driving and 17 mpg mixed driving. Will regular gasoline appreciably affect these numbers?

 

I've used 87 in a 2002 Discovery 2 and a 2007 Range Rover without problems. The computer will probably compensate for reduced octane to some extent through retarding the spark based on knock sensing, but with a 2.0 liter turbocharged engine making nearly 300 HP in a heavy vehicle, I am not going to risk it. I've been using at least 91 (R+M)/ 2 octane. 91 is often not available, so often this involves alternating 93 and 89.

 

i put 93

 

I use 93 in my P400.

 

93 only. Understandably, the ECM and DME will compensate and adjust timing, spark, and fuel mixture to eliminate knocking, but in my minds eye, I would rather the engine run at its best designed efficiency and performance than split dollars for savings at the pump.

 

93 because that’s what’s the engine performs best on. Currently P400

 

The modern engines in the P300/P400 are probably better but my data points:
1) My old Discovery would eat through O2 sensors if I didn't run premium gas. The cost of changing those out far exceeded the price delta of premium.
2) I ran premium in my Acura MDX and got 18-21 MPG. My neighbor had same model and used regular gas. He always complained of barely getting 16 MPG.

Anyway - I have the P300... can't afford to lose any of the "only" 300 HP so I run premium

 

Premium.

If you drive 15k miles a year and average ~18 mpg, assuming an approximate 20c/gallon price delta to get premium it means a whopping extra $183 a year in automotive costs.

YMMV

But yes. Premium is recommended. Not required. Use regular and save the money for something more useful.

 

.....

 

LOL. Absolutely true. Don’t know why I swear the small stuff sometimes.