Fleet total cost of ownership: parking AC vs APU vs bunk heater vs idle (5-year)

• Table of Contents

1. Baseline assumptions
2. Option A: Vethy parking AC (LFP battery)
3. Option B: Diesel APU
4. Option C: Bunk heater only (winter only)
5. Option D: Continued idle (do nothing)

Fleet asset management and procurement teams comparing sleeper-berth comfort options need a complete 5-year total cost of ownership view spanning capex, fuel, maintenance, residual value, and indirect cost (driver retention, insurance, ESG reporting). This page models the four most common options side-by-side using indicative numbers for a representative Class 8 long-haul tractor.

Baseline assumptions

Modelled tractor: Class 8 long-haul sleeper, US national fleet, 110 000 miles/year, 1 200 hours/year sleeper-berth time, $4.20/gallon diesel, $30/hour fully-loaded driver cost. Geographic mix: 60% southern/hot-region, 40% northern/cold-region. Five-year first-life. Numbers indicative for modelling — substitute actual fleet numbers in the ROI calculator for fleet-specific decisions.

Option A: Vethy parking AC (LFP battery)

Capex: $5 200 equipment + $850 install = $6 050. 5-year fuel savings vs idle baseline: $14 000-22 000. 5-year maintenance: $400 (filter, optional refrigerant top-up at year 3). Residual at trade-in: $1 200 uplift. Driver retention indirect benefit (1-2 fewer turnover events/tractor over 5 years): $4 000-8 000. Insurance anti-idle discount: $1 000-2 500 over 5 years. Net 5-year TCO benefit vs idle baseline: $13 000-26 000 per tractor.

Option B: Diesel APU

Capex: $8 500 equipment + $1 200 install = $9 700. 5-year fuel savings vs idle baseline: $11 000-17 000 (APU still burns diesel, but at 0.2-0.3 gal/hr vs idle 0.8-1.0 gal/hr). 5-year maintenance: $2 800-4 200 (APU oil change, filter, glow plug, generator brushes). Residual at trade-in: $500 uplift (depreciating asset class). Driver retention indirect: $3 000-6 000. Insurance discount: $800-2 000. Net 5-year TCO benefit vs idle baseline: $4 000-12 000 per tractor.

Option C: Bunk heater only (winter only)

Capex: $1 800 equipment + $450 install = $2 250. 5-year fuel savings vs idle baseline: $3 000-5 000 (winter-only operation, no cooling capability). 5-year maintenance: $200. Residual at trade-in: $200 uplift. Driver retention indirect: minimal — does not address summer comfort which is the primary driver-retention complaint in hot regions. Insurance discount: $300-700. Net 5-year TCO benefit vs idle baseline: $1 000-3 000 per tractor (heating only). Best fit: cold-region-only fleets without summer-heat exposure.

Option D: Continued idle (do nothing)

Capex: $0. 5-year fuel cost vs no idle: -$15 000-23 000 (this is the cost of doing nothing). 5-year maintenance: increased DPF regen, oil interval shortening, engine-hour-driven PM intervals — $1 200-2 500 incremental. Driver retention indirect: -$5 000-10 000 (idle noise and uneven sleep is a top retention complaint). Insurance: no discount; potential anti-idle violation premium in regulated states. Net 5-year TCO penalty vs any active option: -$17 000-32 000 per tractor.

Frequently asked questions

Which option has the best 5-year TCO?

Vethy parking AC typically delivers the best 5-year TCO across most fleet duty cycles: $13 000-26 000 net benefit vs idle baseline. Diesel APU is moderate ($4 000-12 000). Bunk heater alone is best fit only for cold-region-only fleets. Continued idle is the worst option by every metric.

Why does Vethy beat diesel APU on TCO?

Lower 5-year maintenance ($400 vs $2 800-4 200 for APU oil/filter/glow plug/brushes), better fuel reduction (zero on-tractor diesel burn vs APU 0.2-0.3 gal/hr), higher residual at trade-in, and stronger driver retention benefit. APU still makes sense in very long-duration hotel-load applications above battery capacity but is generally outperformed by LFP-battery parking AC for typical sleeper-berth duty cycles.

What if my fleet is cold-region only?

Bunk heater alone can be the best fit if you genuinely have no summer-heat exposure. Most US fleets running national lanes have meaningful southern exposure even in winter (Texas, Georgia, Florida runs) and benefit from parking AC. Confirm with your route data.

Where do I get fleet-specific numbers?

Run the fleet ROI calculator with your fleet's actual fuel price, idle baseline, driver wage, and turnover rate. The 5-year TCO numbers above are indicative for modelling; fleet-specific numbers can vary materially.