From the long trips I've done in the 180 and 105 at consistent speed and conditions between refills, the trends I've noticed is the 3/4 mark on the guage is more like 2/3 in the tank. At 1/4 mark, it's 1/3 left in the tank. This is a rough calulcation using the real distances travelled. Hence, the guage appears to drop slowly 3/4, then feels like it drops crazy fast to 1/4. The final 1/4 tank covers about the same distance as the first 1/4.
OP, with 134 mi covered at the 3/4, you should see 260 mi by the time guage reaches 1/4 mark and 390 mi if you run the tank down to the reserve. On 50l of fuel, that could be 35mpg. Assuming the driving conditions stay the same
