Rigs / Newmar / Essex / 4578 Newmar Essex 4578 Class A built 2021–23 Better build tier Patient search on the used market
WHAT ONE COSTS
— price not published
The maker never published an MSRP for this floorplan. Unknown is not cheap — treat any asking price against comparable models, not against zero.
THE SPECS
Length 44.8 ft
Height (incl. A/C) 13.3 ft
Width 8.5 ft
Interior height 6.9 ft
GVWR 54,000 lb
Dry weight 46,700 lb
Cargo capacity 7,300 lb
Sleeps 4
Slide-outs 3
Fresh water 105 gal
Grey water 80 gal
Black water 60 gal
Air conditioning 45,000 BTU
Fuel 150 gal
Engine / chassis Cummins X15 605 hp diesel pusher
Generator Cummins Onan 12.5 kW diesel
A missing row means the maker never published that figure — unknown, not zero.
WHERE PEOPLE SLEEP
1× Rear king bed(Permanent) 72×80 1× 87 in. side hide-a-bed sofa(Convertible) — HOW IT'S BUILT — 4/5
Walls Laminated fiberglass
Frame Steel
Roof Walk-on
Underbelly Enclosed
Newmar (Better tier): Newmar
YEAR BY YEAR — WHAT CHANGED
YEARS GVWR DRY MSRP 2021–22 54,000 lb 47,000 lb — 2023 54,000 lb 46,700 lb —
2021 Introduced 2024 Discontinued FINDING ONE
Patient search — weeks of watching, and probably some travel. Estimated from build volume and production span — not a count of live listings.
THE READ
Three-year plan dropped when the 2024 line was cut to four layouts.
OTHER ESSEX FLOORPLANS
4501 · 54,000 lb · sleeps 4 4503 · 54,000 lb · sleeps 4 4507 · 54,000 lb · sleeps 4 4513 · 54,000 lb · sleeps 4 4518 · 54,000 lb · sleeps 4 4519 · 54,000 lb · sleeps 4 4521 · 54,000 lb · sleeps 5 4531 · 54,000 lb · sleeps 4 4533 · 54,000 lb · sleeps 4 4534 · 54,000 lb · sleeps 4 4536 · 54,000 lb · sleeps 4 4537 · 54,000 lb · sleeps 4 4542 · 52,000 lb · sleeps 4 4543 · 54,000 lb · sleeps 4 the whole line → Is the 4578 your #1 — or just a spec sheet?
These are the facts. Whether it beats the other six thousand rigs for you depends on what you care about — set your priorities as sliders and watch the whole market re-rank around them. Nothing gets hidden, everything gets explained.
Rank it against your setup → Data compiled from manufacturer spec sheets, retrieved 2026-07.