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US diesel $4.049 per gallonWeek ending Aug 17, 2026 · EIA
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PACCAR MX-13

12.9 litre2010 to presentGHG17 (2017)

PACCAR's own engine, built on DAF architecture, and now the default in a large share of new Kenworths and Peterbilts. Compact graphite iron block, lighter than a 15 litre, and competitive on fuel with the Detroit.

Output

405-510 hp

1450-1850 lb-ft peak torque

Fuel per mile

$0.533

at 7.6 mpg and $4.049 a gallon

Fuel a year

$63,932

over 120,000 miles

In-frame overhaul

$21k-$30k

rough, and shop rates move it

In the exhaust

DPF and SCR

The first greenhouse gas phase targets the whole vehicle rather than the engine, so this era is as much about aerodynamics, tyres and axle ratios as combustion. Downspeeding becomes standard: tall gears, low cruise revs.

Known issues

EGR valve and cooler, aftertreatment sensors, and a parts channel that runs through PACCAR dealers rather than the independent network, which matters when you break down somewhere without one.

Verdict

A good engine with a real logistics caveat: check where the nearest PACCAR dealer is on the lanes you actually run before you choose it over a Cummins.