# Grand Design Momentum M-Class 399M

Momentum M-Class 399M is a toy hauler floor plan by Grand Design.

## Specs (2026 model year)

| Spec | Value |
| --- | --- |
| Length | 44 ft 10 in |
| Sleeps | 6 |
| Slide-outs | 3 |
| Dry weight | 18,000 lbs |
| GVWR | 22,500 lbs |
| MSRP | $174,278 |

## Model years

2026. Year-specific specs: `https://rvenvy.com/toy-haulers/grand-design/momentum-m-class/399m?year={year}`

## Overview

The Grand Design Momentum M-Class 399M gives the garage a starring role, with a spacious toy-hauler layout that extends outdoor living through its second patio awning and third LED-lit awning. Inside, residential touches include hardwood cabinet doors, a recliner sofa with adjustable headrests, a fireplace with electric heat, and a smart sink with a cutting board, strainer, and glass rinser. A full bath, central vacuum, enclosed heated storage, 6-point hydraulic leveling, and heavy-duty H-rated running gear round out a capable setup for extended trips.

## Floor plan tags

toy hauler

## Inventory

13 units currently for sale priced $119,995 to $153,899: https://rvenvy.com/toy-haulers/grand-design/momentum-m-class/399m/inventory

## Pricing report

12 of 13 units have a posted asking price across 5 dealers. These are asking prices, not sale prices.

| Condition | Units | Median asking price |
| --- | --- | --- |
| New | 12 | $135,969 |

### Asking price distribution ($2,000 bands)

| Price band | Units |
| --- | --- |
| $119,000–$120,999 | 1 |
| $121,000–$122,999 | 0 |
| $123,000–$124,999 | 2 |
| $125,000–$126,999 | 0 |
| $127,000–$128,999 | 0 |
| $129,000–$130,999 | 2 |
| $131,000–$132,999 | 0 |
| $133,000–$134,999 | 0 |
| $135,000–$136,999 | 3 |
| $137,000–$138,999 | 2 |
| $139,000–$140,999 | 0 |
| $141,000–$142,999 | 0 |
| $143,000–$144,999 | 0 |
| $145,000–$146,999 | 1 |
| $147,000–$148,999 | 0 |
| $149,000–$150,999 | 0 |
| $151,000–$152,999 | 0 |
| $153,000–$154,999 | 1 |

- Median time on lot: 179 days (a lower bound — a unit may have been listed before we first saw it).
- 2 of 13 units cut their asking price in the last 30 days, by a median of 52%.

Floor plan diagram: https://images.rvenvy.com/f6fd90b00baf431b3ee1fcea7bf365652fce8d13bb3afc6a2bb88c4d4878e622/1024.webp

Canonical page: https://rvenvy.com/toy-haulers/grand-design/momentum-m-class/399m